Use of renewable energy in ammonia synthesis

ABSTRACT

An ammonia synthesis plant comprising: a feed pretreating section operable to pretreat a feed stream; a syngas generation section operable to reform the feed stream to produce a reformer product stream; a shift conversion section operable to subject the reformer product stream to the water gas shift reaction, to produce a shifted gas stream comprising more hydrogen than the reformer gas stream; a purification section operable to remove at least one component from the shifted gas stream, and provide an ammonia synthesis feed stream; and/or an ammonia synthesis section operable to produce ammonia from the ammonia synthesis feed stream, wherein the ammonia synthesis plant is configured such that, relative to a conventional ammonia synthesis plant, more of the energy required by the ammonia synthesis plant or one or more sections thereof is provided by a non-carbon based energy source, a renewable energy source, and/or electricity.

TECHNICAL FIELD

The present disclosure relates to the use of renewable energy in ammoniasynthesis; more particularly, the present disclosure relates to theelectrification of an ammonia synthesis plant; still more particularly,the present disclosure relates to a reduction in environmentalemissions, such as carbon dioxide, by reducing the combustion ofhydrocarbons (e.g., natural gas/fossil fuels) for fuel in an ammoniasynthesis plant.

BACKGROUND

Chemical synthesis plants are utilized to provide a variety ofchemicals. Often, a dedicated fuel is burned or ‘combusted’ to provideheat of reaction for chemical synthesis, energy to heat one or moreprocess streams, energy to vaporize liquids (e.g., boil water used as adiluent), energy to do work (e.g., drive a compressor or pump), orenergy for other process operations throughout the chemical synthesisplant. Such burning or combustion of fuels results in the production offlue gases, which can be harmful to the environment, and also results ina loss of energy efficiency of the process. Likewise, steam is oftenconventionally utilized as a plant-wide heat and/or energy transferfluid within chemical synthesis plants. The steam utilized for the heatand/or energy transfer is often produced via the combustion of a fuel,resulting in the production of additional flue gas and further energyefficiency losses during the chemical synthesis. Additionally, the useof a material that could otherwise be utilized as a reactant forcombustion as a fuel also reduces an amount of the desired chemicalproduct produced in the chemical synthesis plant from a given amount ofthe material. Accordingly, a need exists for enhanced systems andmethods of chemical synthesis whereby an amount of fuels, especiallyfossil fuels, burned to provide energy is reduced or eliminated.Desirably, such systems and methods also provide for an increase inenergy efficiency and/or a decrease in emissions, such as emissions ofgreenhouse gases (GHG), by the chemical synthesis plant.

SUMMARY

Herein disclosed is an ammonia synthesis plant comprising: a feedpretreating section operable to pretreat a feed stream comprisingnatural gas, methane, propane, butane, LPG, naphtha, coal, petroleumcoke, or a combination thereof; a syngas generation section comprisingone or more reformers operable to reform the feed stream to produce areformer product stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising one or more shift reactors operable tosubject the reformer product stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and/or an ammoniasynthesis section comprising one or more ammonia synthesis reactorsoperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured such that, relative toa conventional ammonia synthesis plant, more of the energy required bythe ammonia synthesis plant, the feed pretreating section, the syngasgeneration section, the shift conversion section, the purificationsection, the ammonia synthesis section, or a combination thereof, isprovided by a non-carbon based energy source, a renewable energy source,and/or electricity.

Also disclosed herein is an ammonia synthesis plant comprising: a feedpretreating section operable to pretreat a feed stream comprising acarbon-containing material, such as natural gas, methane, propane,butane, LPG, naphtha, coal and/or petroleum coke; a syngas generationsection comprising one or more reformers operable to the pretreated feedstream to produce a reformer gas stream comprising carbon monoxide andhydrogen; a shift conversion section comprising at least one shiftreactor operable to subject the reformer gas stream to the water gasshift reaction, to produce a shifted gas stream comprising more hydrogenthan the reformer gas stream; a purification section operable to removeat least one component from the shifted gas stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen; and/oran ammonia synthesis section comprising at least one ammonia synthesisreactor operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured such that amajority of the net external energy required by the feed pretreatingsection, the syngas generation section, the shift conversion section,the purification section, the ammonia synthesis section, or acombination thereof, is provided by electricity.

Further disclosed herein is an ammonia synthesis plant comprising: afeed pretreating section operable to pretreat a feed stream; a syngasgeneration section comprising one or more reformers operable to reformmethane to produce a reformer gas stream comprising carbon monoxide andhydrogen; a shift conversion section comprising one or more shiftreactors operable to subject the reformer gas stream to the water gasshift reaction, to produce a shifted gas stream comprising more hydrogenthan the reformer gas stream; a section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and/or an ammoniasynthesis section comprising one or more ammonia synthesis reactorsoperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured such that no steam isutilized for mechanical work.

Also disclosed herein is an ammonia synthesis plant comprising: a feedpretreating section operable to pretreat a feed stream; a syngasgeneration section comprising one or more reformers operable to reformmethane to produce a reformer gas stream comprising carbon monoxide andhydrogen; a shift conversion section comprising one or more shiftreactors operable to subject the reformer gas stream to the water gasshift reaction, to produce a shifted gas stream comprising more hydrogenthan the reformer gas stream; a section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and/or an ammoniasynthesis section comprising one or more ammonia synthesis reactorsoperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured such that no flue gasis produced.

Further disclosed herein is an ammonia synthesis plant comprising: afeed pretreating section operable to pretreat a feed stream; a syngasgeneration section comprising one or more reformers operable to reformmethane to produce a reformer gas stream comprising carbon monoxide andhydrogen; a shift conversion section comprising one or more shiftreactors operable to subject the reformer gas stream to the water gasshift reaction, to produce a shifted gas stream comprising more hydrogenthan the reformer gas stream; a purification section operable to removeat least one component from the shifted gas stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen; and/oran ammonia synthesis section comprising one or more ammonia synthesisreactors operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured for nocombustion other than optionally within an autothermal reformer (ATR) ofthe syngas generation section.

Also disclosed herein is an ammonia synthesis plant comprising anelectrically heated steam reformer operable to provide hydrogen and anelectrically powered air separation unit (ASU) operable to providenitrogen for the ammonia synthesis.

Further disclosed herein is an ammonia synthesis plant comprising: apurification section operable to receive a hydrogen stream and a streamof nitrogen, wherein the stream of nitrogen is optionally from a sourcedisparate from a source of the hydrogen stream, optionally remove atleast one component from the hydrogen stream and/or the nitrogen stream,and provide an ammonia synthesis feed stream comprising hydrogen andnitrogen; and an ammonia synthesis section comprising one or moreammonia synthesis reactors operable to produce ammonia from the ammoniasynthesis feed stream, wherein the ammonia synthesis plant is configuredsuch that a majority of the net external energy supplied for compressionand heating within the purification section, the ammonia synthesissection, or the entire ammonia synthesis plant, is supplied from anon-carbon based energy source, a renewable energy source, electricity,and/or renewable electricity.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1 shows a conceptual diagram of a typical prior art chemicalprocess;

FIG. 2 shows a conceptual diagram of a chemical process powered byrenewable energy, according to embodiments of this disclosure;

FIG. 3 shows a block flow diagram of a generalized ammonia synthesisplant or process I, according to embodiments of this disclosure;

FIG. 4 shows a block flow diagram of an exemplary ammonia synthesisplant or process II, according to embodiments of this disclosure;

FIG. 5 shows a block flow diagram of a conventional ammonia synthesisplant or process III, discussed in Comparative Example 1 of thisdisclosure;

FIG. 6 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process IV comprising electric compressors,according to the embodiment of Example 1 of this disclosure;

FIG. 7 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process V comprising electric compressors andan electric furnace, according to the embodiment of Example 2 of thisdisclosure;

FIG. 8 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process VI comprising electric compressorsand an electric reboiler, according to the embodiment of Example 3 ofthis disclosure;

FIG. 9 shows a block flow diagram of a near completely electrifiedammonia synthesis plant or process VII comprising electric compressors,an electric reformer, and an electric reboiler, according to theembodiment of Example 4 of this disclosure;

FIG. 10 shows a block flow diagram of a conventional ammonia synthesisplant or process VIII, discussed in Comparative Example 2 of thisdisclosure;

FIG. 11 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process IX comprising electric compressors,according to the embodiment of Example 5 of this disclosure;

FIG. 12 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process X comprising electric compressors andan electric reformer, according to the embodiment of Example 6 of thisdisclosure;

FIG. 13 shows a block flow diagram of an exemplary partially electrifiedammonia synthesis plant or process XI comprising electric compressorsand an electric reboiler, according to the embodiment of Example 7 ofthis disclosure;

FIG. 14 shows a block flow diagram of a near completely electrifiedammonia synthesis plant or process XII comprising electric compressors,an electric reformer, and an electric reboiler, according to theembodiment of Example 8 of this disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed compositions, methods, and/or products may be implementedusing any number of techniques, whether currently known or not yet inexistence. The disclosure should in no way be limited to theillustrative implementations, drawings, and techniques illustratedhereinbelow, including the exemplary designs and implementationsillustrated and described herein, but may be modified within the scopeof the appended claims along with their full scope of equivalents.

While the following terms are believed to be well understood by one ofordinary skill in the art, the following definitions are set forth tofacilitate explanation of the presently disclosed subject matter. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood to one of ordinary skill in theart to which the presently disclosed subject matter belongs.

As utilized herein, an ‘intermittent energy source’ or ‘IES’ is anysource of energy that is not continuously available for conversion intoelectricity and outside direct control because the used energy cannot bestored or is economically undesirable. The availability of theintermittent energy source may be predictable or non-predictable. Arenewable intermittent energy source is an intermittent energy sourcethat is also a source of renewable energy, as defined hereinbelow.‘Intermittent electricity’ refers to electricity produced from an IES.

As utilized herein, ‘renewable energy’ and ‘non-fossil based energy(ENF)’ includes energy derived from a sustainable energy source that isreplaced rapidly by a natural, ongoing process, and nuclear energy.Accordingly, the terms ‘renewable energy’ and ‘non-fossil based energy(ENF)’ refer to energy derived from a non-fossil fuel based energysource (e.g., energy not produced via the combustion of a fossil fuelsuch as coal or natural gas), while ‘non-renewable’ or ‘fossil basedenergy (EF)’ is energy derived from a fossil fuel-based energy source(e.g., energy produced via the combustion of a fossil fuel). Fossilfuels are natural fuels, such as coal or gas, formed in the geologicalpast from the remains of living organisms. Accordingly, as utilizedherein, ‘renewable’ and ‘non-fossil based energy (ENF)’ include, withoutlimitation, wind, solar power, water flow/movement, or biomass, that isnot depleted when used, as opposed to ‘non-renewable’ energy from asource, such as fossil fuels, that is depleted when used. Renewableenergy thus excludes fossil fuel based energy (EF) and includesbiofuels.

As utilized herein, ‘non-carbon based energy (ENC)’ is energy from anon-carbon based energy source (e.g., energy not produced via thecombustion of a carbon-based fuel such as a hydrocarbon), while carbonbased energy (EC) is energy from a carbon-based energy source (e.g.,energy produced via the combustion of a carbon-based fuel such as ahydrocarbon). Nuclear energy is considered herein a renewable,non-fossil (ENF) based energy and a non-carbon based energy (ENC).Carbon-based energy (EC) can thus be renewable (e.g., non-fossil fuelbased) or non-renewable (e.g., fossil fuel-based). For example, variouscarbon-based biofuels are herein considered renewable, carbon-basedenergy sources.

As utilized herein, ‘renewable electricity’ indicates electricityproduced from a renewable energy source, while ‘non-renewableelectricity’ is electricity produced from a non-renewable energy source.As utilized herein ‘non-carbon based electricity’ indicates electricityproduced from a non-carbon based energy source, while ‘carbon-basedelectricity’ is electricity produced from a carbon-based energy source.

For example, in embodiments, renewable electricity and/or heatthroughout the herein-disclosed ammonia synthesis plant can be providedby the combustion of renewable hydrocarbons that come from renewable(e.g., biological) sources. For example, renewable electricity can, inembodiments, be produced via the combustion of an ENF/EC energy sourcecomprising methane produced in a digester fed with agricultural wastes.Likewise, in embodiments, an ENF/EC energy source comprising synthesisgas produced using short cycle carbon waste materials can be utilized asa fuel (e.g., combusted to produce renewable electricity and/or heat).Desirably, the carbon dioxide generated by such combustion is recaptured(e.g., by the growth of a new crop).

As utilized herein, ‘externally’ combusting a fuel refers to combustinga fuel outside of a reactor, e.g., in a furnace. Combustion as a part ofthe primary reaction (e.g., combustion which takes place with reformingin autothermal reforming (ATR)) would not be considered ‘externally’combusting. As utilized herein, a ‘dedicated’ fuel is a fuel or portionof a feed stream introduced solely to provide fuel value (e.g.,combustion heat) and not be converted into product.

As utilized herein, ‘heat transfer steam (SHT)’ indicates steam producedsolely or primarily as an energy or heat transfer medium (e.g., steamnot utilized as a diluent and/or reactant).

As utilized herein, ‘net’ heat input or removal refers to heat input orremoval that results in primary energy consumption, e.g., heat input orremoval not provided from another section or stream of the plant, e.g.,not provided via heat exchange with another process stream. Similarly,‘net’ energy refers to energy that results in primary energyconsumption, e.g., energy not provided from another section or stream ofthe plant, e.g., thermal energy not provided via heat exchange withanother process stream.

As utilized herein, ‘powering’ indicates supplying with mechanicaland/or electrical energy.

As utilized herein, ‘heating’ indicates supplying with thermal energy.As utilized herein ‘cooling’ indicates the removal of thermal energytherefrom. As utilized herein, ‘direct’ heating or cooling refer toheating or cooling without the use of a heat transfer medium/fluid;‘indirect’ heating or cooling refer to heating or cooling via a heattransfer medium/fluid.

As utilized herein, ‘most’ or ‘a majority’ indicates more than 50% ormore than half.

As utilized herein, a ‘desired’ parameter (e.g., desired temperature)may refer to an intended or target value for the parameter, for examplea predetermined value such as a set-point value used for processcontrol.

Amount of electricity consumed: References to consumption of electricitymay refer to a rate at which electricity is used (e.g., in MW), asmeasured at a particular location. For example, a rate may be calculatedat the boundary of each electrified furnace or at an overall olefinsynthesis plant boundary. This calculation may consider all electricityused within that location.

Flue gas: A mixture of gases that may be produced by the burning of fuelor other materials in a power station and/or industrial plant, where themixture of gases may be extracted via ducts.

Flue gas heat recovery: Flue gas heat recovery may refer to theextraction of useful thermal energy from hot flue gases, for example bypassing said hot flue gas over one or more heat exchangers to raise thetemperature of a cooler process fluid and/or change the phase of saidfluid (e.g., boil water to raise steam). Any energy remaining in theflue gas after any flue gas heat recovery may be termed flue gas(energy) loss. A flue gas heat recovery section may be the equipment andcorresponding location of said equipment used to recover flue gas heat.A lack of flue gas heat recovery section may mean there is no equipmentor area where heat is recovered from hot flue gases.

Convection section: A convection section may be a portion of a furnace(e.g., steam cracking furnace or reforming furnace) where heat isrecovered from hot flue gases by convective heat transfer. A lack ofconvection section may mean that there is no equipment or area whereheat is recovered by convective heat transfer from hot flue gases.

“Steam-free” or “Substantially Steam-free”: “Steam free” may refer to aprocess where steam is not used to transfer energy from one processoperation to another, or to bring energy into the process from outside.“Substantially steam-free” may mean that the use of steam to transferenergy from one process operation to another or to bring energy into theprocess from outside has been minimized such that the sum of all energytransfers using steam amount to less than approximately 10%,approximately 20%, or approximately 30% of the net energy provided.Steam used as a reactant, a diluent, obtained as a product, or directlymixed with a process stream may be termed “process steam” and is notincluded in this definition.

Primary energy transfer medium: A primary energy transfer medium may bea substance that is used to move energy in the form of thermal energyfrom one process operation to another, or to bring energy into aprocess. Note that a substance may serve more than one purpose in aprocess such as acting as a reactant or reaction diluent whilst alsoacting as a medium to transfer heat from one process operation toanother. In such instances, the use of steam as reactant or diluent maybe considered primary and the effect of also transferring heat may beconsidered secondary.

Resistive heating: Resistive heating may be heating by means of passingelectric current through resistive units.

Inductive heating: Induction heating may be a process of heating anelectrically conducting object (usually a metal) by electromagneticinduction.

Radiant heating: Radiant heating may be a process of heating an objectvia radiation from one or more hotter objects.

Externally combusting: Externally combusting may mean burning fuel togenerate heat and transferring this heat to a process fluid across asurface (e.g., a tube wall) such that combustion products do not mixwith the process fluid.

Thermoelectric device: A thermoelectric device may be a device for thedirect conversion of temperature differences to electric voltage (orvice versa) across a thermocouple.

Isothermal operation: Isothermal operations may be operations at aconstant temperature. Isothermal operation can keep temperature within0.5%, 1%, 2%, 3%, 4%, 5% up to 10% of the predetermined operationtemperature.

Convective heat transfer: Convective heat transfer may be the movementof heat from one place to another by the movement of a fluid or fluids.

Although the majority of the above definitions are substantially asunderstood by those of skill in the art, one or more of the abovedefinitions can be defined hereinabove in a manner differing from themeaning as ordinarily understood by those of skill in the art, due tothe particular description herein of the presently disclosed subjectmatter.

FIG. 1 shows a conceptual diagram of a typical traditional chemicalprocess. The goal of this process is to convert feed A into product B,although often some byproducts (indicated as stream C) are alsoproduced.

The unit operations used to effect this transformation requiresignificant amounts of energy. Conventionally, this energy is primarilysupplied by burning a fuel, often natural gas, to generate heat, denotedin FIG. 1 as ΔHc (e.g., heat of combustion). This results in theundesirable production and emission of carbon dioxide (CO₂). Additionalenergy may be supplied by the heat of reaction, ΔHr, if the reaction isexothermic; if the reaction is endothermic, an additional amount ofenergy equal to ΔHr will need to be added. The total energy balance mayalso be affected if some byproducts are burned to produce energy,indicated as ΔHbp. However, many chemical processes, even thoseinvolving exothermic reactions, are net energy consumers and thusrequire an external source of energy (typically provided by ahydrocarbon fuel(s)) to provide net process energy.

Electricity is usually only a small external input into most chemicalproduction processes. Internal electrical requirements, such as forlighting or control, are usually so small as to be negligible, and inthose few processes which require large amounts of electricity, forexample, electrochemical reactors (e.g., the chlor-alkali process tomake chlorine (Cl2) and sodium hydroxide (NaOH)), this electricity iscommonly generated within the plant boundaries by the combustion ofhydrocarbons, and, even when not generated within the plant boundaries,if the electricity is obtained by the combustion of hydrocarbons ratherthan renewably, such use of electricity is equivalent in terms of energyefficiency and CO₂ emissions to on-site production of the electricityvia hydrocarbon combustion.

Within most chemical production processes, energy consumption canconveniently be divided into three main categories. In the first suchbroad category, referred to herein as first category C1, heat issupplied directly as thermal energy by the combustion of a fuel (e.g.,natural gas/fossil fuels) in a furnace. (As utilized, here, ‘directly’indicates the absence of an intermediate heat transfer medium, such assteam.) These furnaces are often operated at high temperature andrequire large heat fluxes. The energy efficiency of such furnaces islimited by the heat losses in the furnace flue gas. Even where theseheat losses are minimized by the cooling of the flue gas to recoverenergy, for example to generate steam or provide process heating, theconversion of the chemical energy contained in the fuel to usablethermal energy generally does not exceed 85 to 90%, even withsubstantial investment and loss of design and operating flexibility.

The second broad category, referred to herein as second category C2, ofenergy consumption in chemical processes comprises the heating ofvarious chemical streams, primarily either to raise the temperaturethereof to a desired reaction temperature or to provide energy forseparations, most commonly distillation. Although some of this heat canbe obtained by exchange with other chemical streams, it is mosttypically provided either by steam generated directly by the combustionof hydrocarbon fuels (e.g., natural gas/fossil fuels) or by heattransfer from the flue gas from high-temperature furnaces (e.g., fromcategory C1). Most modern chemical processes include a relativelycomplicated steam system (or other heat transfer fluid system which willgenerically be referred to herein for simplicity as a steam heattransfer system) to move energy from where it is in excess to where itis needed. This steam system may include multiple pressure levels ofsteam to provide heat at different temperatures, as well as a steam andcondensate recovery system, and is subject to corrosion, fouling, andother operational difficulties, including water treatment andcontaminated condensate disposal. The fraction of the energy containedin the steam that can be used to heat process streams is generallylimited to 90 to 95% by practical constraints on heat transfer, steamcondensation, and boiler water recycle. If the steam was generated by anon-purpose external boiler, at most 80 to 85% of the chemical energycontained in the fuel will be used as heat by the chemical process,since an additional 10 to 15% or more will be lost to flue gas as infirst category C1.

The third major category, referred to herein as third category C3, ofenergy usage in chemical processes is energy utilized to performmechanical work. This work is primarily utilized for pressurizing andmoving fluids from one place to another, and is used to drive rotatingequipment such as pumps, compressors, and fans. This third category C3also includes refrigeration equipment, since it is primarily powered bycompression. In most chemical facilities, the energy for this work isprovided by steam, obtained either by heat transfer with hot processstreams, by heat transfer with partially-cooled flue gas streams from afurnace (e.g., in the convection section) in category C1, or directlyfrom the combustion of hydrocarbons (e.g., natural gas/fossil fuels) inan on-purpose external boiler. Because of limitations on the conversionof thermal energy to mechanical work, the energy efficiency of theseuses relative to the contained chemical energy of the hydrocarbons usedas fuel is low, typically only 25 to 40%.

It has been unexpectedly discovered that using electricity (e.g.,renewable and/or non-renewable electricity) to replace energy obtainedfrom a hydrocarbon fuel in a chemical process can improve the process byincreasing overall energy efficiency, while decreasing carbon dioxideemissions. In some cases, using electricity (e.g., renewable and/ornon-renewable electricity) to replace energy obtained from a hydrocarbonfuel in a chemical process can also improve reliability and operability,decrease emissions of, for example, NOx, SOx, CO, and/or volatileorganic compounds, and/or decrease production costs (e.g., if low-costelectricity is available).

According to embodiments of this disclosure, heat conventionallysupplied as thermal energy by the combustion of a fuel (e.g., naturalgas/fossil fuels) in a furnace and/or other heating in first category C1is replaced by electrical heating. Electrical heat, electrical heating,generating heat electrically, electrical heater apparatus, and the likerefer to the conversion of electricity into thermal energy available tobe applied to a fluid. Such electrical heating includes, withoutlimitation, heating by impedance (e.g., where electricity flows througha conduit carrying the fluid to be heated), heating via ohmic heating,plasma, electric are, radio frequency (RF), infrared (IR), UV, and/ormicrowaves, heating by passage over a resistively heated element,heating by radiation from an electrically-heated element, heating byinduction (e.g., an oscillating magnetic field), heating by mechanicalmeans (e.g. compression) driven by electricity, heating via heat pump,heating by passing a relatively hot inert gas or another medium overtubes containing a fluid to be heated, wherein the hot inert gas or theanother medium is heated electrically, or heating by some combination ofthese or the like.

According to embodiments of this disclosure, the utilization of steam(or another heat transfer fluid) as in second category C2 is eliminatedand/or any steam (or other fluid) utilized solely as an intermediateheat transfer medium is electrically produced or heated (e.g., viaelectrical heating of water).

According to embodiments of this disclosure, conventional rotatingequipment (e.g., steam turbines) utilized in third category C3 isreplaced with electrically driven apparatus. According to embodiments ofthis disclosure, heat removal in third category C3 is replaced byelectrically-powered heat removal, e.g., cooling and/or refrigeration.Electrical cooling, electrical coolers, removing heat electrically,electrical cooling or refrigeration apparatus, and the like refer to theremoval of thermal energy from a fluid. Such electrical coolingincludes, without limitation, cooling by electrically powered apparatus.For example, and without limitation, electrical cooling can be providedby powering a refrigeration cycle with electricity, wherein arefrigerant is compressed by an electrically powered compressor. Asanother example, electrical cooling can be provided by powering acooling fan that blows air, wherein the air cools a process fluid orelement. In embodiments, electrical heating and cooling can be effectedby any electrical source.

FIG. 2 is a schematic of a chemical process powered by renewable energy,according to embodiments of this disclosure. As shown in FIG. 2, aprocess driven by renewable energy can, in embodiments, appear similarto a conventional chemical process. However, a portion, a majority, or,in some cases, substantially all of the energy input supplied by fuelcan be replaced by renewable energy and/or by renewable electricity.Such replacement of fuel input by non-carbon based energy, renewableenergy, and/or renewable electricity will allow for a significantdecrease in CO₂ emissions, in embodiments. In embodiments, any availableform of renewable energy can be employed. However, the gains may begreatest if renewable electricity is utilized. The renewable energy canbe obtained from, for example and without limitation, solar power, windpower, or hydroelectric power. Other types of renewable energy can alsobe applied in chemical plants according to embodiments of thisdisclosure. For example, in embodiments, concentrated solar power,geothermal energy, and/or the use of direct solar heating can be used toprovide thermal energy and to decrease CO₂ emissions.

One of the main advantages to supplying needed energy via (e.g.,renewable) electricity can be that the energy efficiency of the processwill increase. Table 1 shows the energy efficiency of unit operationsexemplifying the three categories of energy use in a chemical plantdescribed above as C1, C2, and C3. It can be seen from Table 1 that theefficiency of each of the three categories of energy consumption isgreater when electrical power is used. The gain can be greatest whensteam drives for rotating equipment are replaced, according toembodiments of this disclosure, with electrical motors (as in thirdcategory C3, discussed hereinabove), which can operate with as much asthree times the energy efficiency of steam drives. These gains are onlyrealized when the electricity is derived from non-carbon based renewablesources, since the generation of electricity from carbon-based fuelcombustion is only 30 to 45% energy efficient. Energy efficiency gainswhen using renewable electricity for heating applications (as in firstcategory C1 and second category C2, discussed hereinabove) are smaller,but still significant. The net result is that less total energy will beused if renewable energy is used in place of carbon-based fuels (e.g.,natural gas or other hydrocarbons).

TABLE 1 Energy Efficiency of Unit Operations Efficiency from Efficiencyfrom Hydrocarbon Electricity According to Use Combustion This DisclosureC1: Direct Heating up to 80-90% 95+% C2: Heating with Steam up to 80-95%95+% C3: Rotating Equipment 25-40% 90-95% 

According to this disclosure, non-carbon based energy, renewable energy,and/or electricity (e.g., from renewable and/or non-renewable sources)can be utilized rather than conventional energy sources in categoriesC1, C2, and/or C3 described hereinabove. In embodiments, electrificationis utilized for a majority of or substantially all utilities. Inembodiments, electrification is utilized for a majority of orsubstantially all unit operations. In embodiments, electrification isutilized for a majority of or substantially all utilities and unitoperations. In embodiments, electrification is utilized for a majorityof or substantially all process applications, engines, cooling and/orheating (e.g., electrically driven heat pumps, refrigeration, electricalheating), radiation, storage systems, or a combination thereof.

In embodiments, the non-carbon based and/or renewable energy sourcecomprises wind, solar, geothermal, hydroelectric, nuclear, tide, wave,ocean thermal gradient power, pressure-retarded osmosis, or acombination thereof. In embodiments, the non-carbon based energy sourcecomprises hydrogen. In embodiments, electricity for electrification asdescribed herein is produced from such a renewable and/or non-carbonbased energy source. In embodiments, some or all of the electricity isfrom a non-renewable and/or carbon-based source, such as, withoutlimitation, combustion of hydrocarbons (e.g., renewable or non-renewablehydrocarbons), coal, or hydrogen derived from hydrocarbons (e.g.,renewable or non-renewable hydrocarbons).

The majority of the CO₂ emitted from most chemical plants is a result offossil fuel combustion to provide energy for the plant. An additionalbenefit of using renewable energy in chemical synthesis as perembodiments of this disclosure is that the amount of greenhouse gasesemitted will be significantly (e.g., by greater than or equal to atleast 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%) reduced relativeto an equivalent conventional chemical synthesis plant or method inwhich hydrocarbons and/or fossil fuel(s) may be combusted. The burningof hydrocarbons (e.g., natural gas, methane) to generate energy resultsin the production of carbon dioxide (CO₂); this production can bereduced or avoided by the use of renewable energy according toembodiments of this disclosure. In embodiments of this disclosure, theamount of CO₂ produced per ton of product produced is reduced to lessthan or equal to about 1.6, 1.5, 1.4, 1.3, 1.2, 1.1, 1.0, 0.75, 0.50,0.30, 0.25, 0.20, 0.10, 0.05, or 0 tons CO₂ per ton chemical product(e.g., ammonia). Furthermore, in embodiments of this disclosure, the useof renewable energy frees up these hydrocarbons (e.g., natural gas,methane) typically burned for fuel for use as a chemical feedstock(e.g., to make ammonia), which is a higher value use.

The use of renewable electricity in the production of chemicals can alsolead to operational advantages. For example, in embodiments, electricpower can be utilized to provide a more accurate and tunable input ofheat, for example to control the temperature profile along a reactor orto change the temperature of specific trays in a distillation column. Inembodiments, the use of electric heating in a reaction section (e.g., ina pyrolysis reaction section) leads to better controlled decoking and/orfaster decoking. Without limitation, other examples include the use ofelectric powered refrigeration units to increase the efficiency ofseparations, and the replacement of inefficient stand-by gas-firedboilers with quick-acting on-demand electrical heaters and steamgenerators and for other utility uses. The use of electricity may alsoallow for significant operational advantages during start-up orshut-down, or to respond to process variability. In general, electricityas an energy source can be applied in specific locations and in preciseand tunable amounts with a rapid response to process changes, leading toa variety of advantages over the use of thermal/combustion energy.

The use of renewable electricity according to embodiments of thisdisclosure can also increase the energy efficiency of utilities thatsupply energy to more than one chemical plant (e.g., an ammoniasynthesis plant and a nearby methanol synthesis plant or an ammoniasynthesis plant and a nearby olefin synthesis plant). For example, ifthe compressors in an air separation unit that provides oxygen andnitrogen to several different production facilities are powered withrenewable electricity, significant energy gains can be achieved relativeto supplying this power with steam derived from the combustion ofnatural gas.

Energy recovery may be provided, in embodiments, via high temperatureheat pumps or vapor recompression. The plant may further comprise heatand/or energy storage, for example, for use when an intermittent energysource (IES) is utilized. In embodiments, waste heat can be upgraded tousable temperature levels via electrically driven heat pumps. In otherembodiments, energy can be recovered as electricity when process streampressures are reduced by using a power-generating turbine instead of acontrol valve. In other embodiments, energy can be recovered aselectricity using thermoelectric devices.

The use of renewable electricity to replace natural gas or otherhydrocarbons as a source of energy, according to embodiments of thisdisclosure, can be done as part of a retrofit of an existing chemicalprocess (e.g., an existing ammonia synthesis plant) or as an integralcomponent of the design of a new chemical plant (e.g., a new ammoniasynthesis plant). In a retrofit, opportunities for using renewableenergy can depend on elements of the existing design, such as the steamsystem; in a retrofit, careful examination of the entire energy balanceand steam system will be required, as electrifying individual pieces ofequipment without regard to these considerations may result in energyinefficiencies. In embodiments, as seen in Table 1, the highestefficiency gains are achieved by replacing steam drives for rotatingequipment (e.g., in third category C3) with electric motors. However,differing objectives may lead to different choices in partialelectrification; in embodiments, in some instances greater CO2reductions at the expense of smaller increases in energy efficiency maysometimes be realized by first replacing hydrocarbon-fired furnaces(e.g., in first category C1). In embodiments, if thermal energy and/orsteam are obtained from more than one hydrocarbon source, the mostadvantageous operation can be achieved by eliminating the most expensiveand/or polluting fuel sources first. How much renewable energy can beincluded and to what extent existing fuel consumption and carbon dioxide(CO2) emissions can be decreased can vary depending on the application,and will be within the skill of those of skill in the art upon readingthis disclosure.

In embodiments, planning for the use of renewable energy in the designof a grass-roots chemical facility (e.g., a grass-roots ammoniasynthesis plant) can allow for more significant opportunities for betterenergy efficiency and lower CO2 emissions. In embodiments, powering allrotating equipment (e.g., in third category C3) with electricity isutilized to realize large gains in energy efficiency. In embodiments,substantially all (or a majority, or greater than 40, 50, 60, 70, 80, or90%) electric heating (e.g., in first category C1 and/or second categoryC2) is utilized, and the inefficiencies due to the loss of heat in fluegas are substantially reduced or even avoided. In embodiments, the useof steam generated via the combustion of a fossil fuel (e.g., in secondcategory C2) can be minimized or avoided altogether. In embodiments, achange in catalyst and/or a modification of reactor operating conditionsis utilized to allow for less heat generation in a reactor and/or theproduction of fewer byproducts that are burned. In embodiments, a plant(e.g., ammonia synthesis plant) design based on the use of renewableelectricity allows for enhanced optimization of separations operations,since the relative costs of compression and refrigeration are changedvia utilization of renewable electricity as per this disclosure. Suchenhanced separations can, in embodiments, also allow for further captureof minor byproducts from vent streams, freeing these minor products upfor further use as feedstocks or products. Furthermore, the use oflow-cost electricity, according to embodiments of this disclosure, mayallow for the introduction of novel technologies such as, withoutlimitation, hybrid gas and electric heaters, variable speed compressordrives, distributed refrigeration, heat pumps, improved distillationcolumns, passive solar heating of fluids, precise control of reactortemperature profiles, new materials of construction, and quench orcooling using electrically refrigerated diluents. If the cost ofelectricity is sufficiently low, utilization of such electricity astaught herein may favor the introduction of new electrochemicalprocesses. For new construction, it may be less capital intensive todrive processes electrically, due, for example, to the lack of a (e.g.,plant-wide) steam distribution system.

According to embodiments of this disclosure, non-carbon based energy,renewable energy, and/or electricity (renewable, non-renewable,carbon-based, and/or non-carbon based electricity) can be used in theproduction of nearly every chemical, including but not limited tomethanol, ammonia, olefins (e.g., ethylene, propylene), aromatics,glycols, and polymers. Non-carbon based energy, renewable energy, and/orelectricity can also be used, in embodiments, in the preparation offeedstocks for chemicals and for fuels production, such as in methyltert-butyl ether (MTBE) synthesis, cracking, isomerization, andreforming. In such embodiments, some (e.g., at least about 10, 20, 30,40, or 50%), a majority (e.g., at least about 50, 60, 70, 80, 90, or95%), or all (e.g., about 100%) of the heating throughout theplant/process or a section thereof can be provided by electrical heatingand/or some (e.g., at least about 10, 20, 30, 40, or 50%), a majority(e.g., at least about 50, 60, 70, 80, 90, or 95%), or all (e.g., about100%) of the cooling throughout the plant/process or a section thereofcan be provided by electrical cooling as described hereinabove.Disclosed hereinbelow is the use of renewable energy, non-carbon basedenergy, and/or electricity in ammonia synthesis applications.

The disclosures of U.S. Provisional Patent Application Nos. 62/792,612and 62/792,615, entitled Use of Renewable Energy in Olefin Synthesis,U.S. Provisional Patent Application Nos. 62/792,617 and 62/792,619,entitled Use of Renewable Energy in Ammonia Synthesis, U.S. ProvisionalPatent Application Nos. 62/792,622 and 62/792,627, entitled Use ofRenewable Energy in Methanol Synthesis, and U.S. Provisional PatentApplication Nos. 62/792,631, 62/792,632, 62/792,633, 62/792,634, and62/792,635, entitled Use of Renewable Energy in the Production ofChemicals, which are being filed on Jan. 15, 2019, are herebyincorporated herein for purposes not contrary to this disclosure.

This disclosure describes an ammonia synthesis plant for producingammonia configured such that a majority of the net energy required byone or more sections, units, groups of like units, or unit operations ofthe ammonia synthesis plant is provided by non-carbon based energy(E_(NC)) from a non-carbon based energy source (e.g., not produced viathe combustion of a carbon-based fuel such as a hydrocarbon), fromrenewable energy (e.g., from non-fossil fuel derived energy (E_(N))),and/or from electricity. The E_(NC) or E_(N) source may, in embodiments,comprise, primarily comprise, consist essentially of, or consist ofelectricity. The E_(NC) or E_(N) source may, in embodiments, comprise,primarily comprise, consist essentially of, or consist of renewableelectricity. In embodiments a portion (e.g., greater than or equal toabout 5, 10, 20, 30, 40, 50), a majority (e.g., greater than or equal toabout 50, 60, 70, 80, 90, or 95%), or all (e.g., about 100%) of the netenergy needed by the overall ammonia synthesis plant, a section of theplant (e.g., a feed pretreating section, a syngas generation section,generally known and also referred to herein at times as a reformingsection, a shift conversion section, a hydrogen and nitrogenpurification section (sometimes referred to herein simply as a ‘hydrogenpurification section’ or simply a ‘purification section’), and/or anammonia synthesis and/or separation section (sometimes simply referredto as an ‘ammonia synthesis section’)), a unit or group of like units(e.g., compressors, power providing units, reboilers, heating units,cooling units, refrigerators, separators, distillation/fractionationcolumns, reformers, shift reactors) or unit operations (e.g.,compressing, powering, reacting (e.g., reforming), separating, heating,cooling) of the plant, or a combination thereof is provided byelectricity, renewable energy (e.g., non-fossil fuel derived energy(E_(NF))), and/or non-carbon based energy (E_(NC)). In embodiments,electricity is provided from a renewable energy source, such as, withoutlimitation, wind (e.g., via wind turbines), solar (e.g., photovoltaic(PV) panels or solar thermal), hydroelectric, wave, geothermal, nuclear,tide, biomass combustion with associated capture of CO₂ in replacementcrops, or a combination thereof. In embodiments a portion (e.g., greaterthan or equal to about 5, 10, 20, 30, 40, 50), a majority (e.g., greaterthan or equal to about 50, 60, 70, 80, 90, or 95%), or all (e.g., about100%) of the electricity, renewable energy (e.g., non-fossil fuelderived energy (E_(NF)), or non-carbon based energy (E_(NC)) needed bythe overall ammonia synthesis plant, a section of the plant (e.g., afeed pretreating section, a syngas generation section, a shiftconversion section, a hydrogen and nitrogen purification section, and/oran ammonia synthesis section and/or ammonia separation section), a unitor a group of like units (e.g., compressors, power providing units,heating units, reboilers, cooling units, refrigerators, separators,distillation/fractionation columns, reactors, shift reactors) or unitoperations (e.g., compressing, powering, reacting, separating, heating,cooling) of the ammonia synthesis plant, or a combination thereof, andconventionally provided in a similar ammonia synthesis plant viacombustion of a fuel, a carbon-based fuel, and/or a fossil fuel and/orthe use of steam (e.g., that was itself generated via the combustion ofsuch a fuel) as an intermediate heat (and/or energy) transfer fluid, isprovided without combusting a fuel, a carbon-based fuel, and/or a fossilfuel and/or without the use of steam generated by the combustion of sucha fuel as an intermediate heat (and/or energy) transfer fluid. Inembodiments, the net energy for the overall plant or one or moresections, units or groups of like units of the plant is provided byelectricity from a renewable energy source. For example, in embodiments,heating is electrically provided via resistive heating or otherwiseconverting electrical energy into thermal energy and/or mechanicalenergy.

In embodiments, an ammonia synthesis plant of this disclosure isconfigured such that a majority (e.g., greater than 50, 60, 70, 80, or90%) of the net energy needed for powering, heating, cooling,compressing, or a combination thereof utilized via the feed pretreatingsystem, one or more syngas generators (e.g. steam reformers), a shiftconversion system, a hydrogen purification system, an ammonia synthesissystem, or a combination thereof, as described hereinbelow, is providedby electricity.

In embodiments, an ammonia synthesis plant according to embodiments ofthis disclosure is a large plant having a production capacity forammonia of greater than or equal to about 100,000 tons per year, 500,000tons per year, or 2,500,000 tons per year. At the larger sizesanticipated in this disclosure, the amount of energy provided by anon-carbon based energy source, a renewable energy source and/orelectricity will be correspondingly large. In embodiments, a partiallyor completely electrified plant according to the methods of thisdisclosure will consume at least 25, 50, 100, 150, 200, 300, 400, or 500MW of electricity.

Although a specific embodiment of an ammonia synthesis plant will beutilized to describe the electrification of an ammonia synthesis plant,as disclosed herein, it is to be understood that numerous arrangementsof units and a variety of ammonia synthesis technologies can beelectrified as per this disclosure, as will be obvious to those of skillin the art upon reading the description herein.

With reference to FIG. 3, which is a block flow diagram of a generalizedammonia synthesis plant I, an ammonia synthesis plant may be consideredto include one or more of the following process sections for convertinga feed stream 5 comprising a carbon-containing material (e.g. naturalgas, naphtha or coal) and optionally 6 comprising a nitrogen containingmaterial (typically air) into an ammonia product stream 55 (andoptionally one or more byproduct streams 41): a feed pretreating section10, a reforming or syngas generation section 20, a shift conversionsection 30, a hydrogen purification section 40, an ammonia synthesissection 50, or a combination thereof. Such sections will be describedbriefly in the next few paragraphs, and in more detail hereinbelow.

As indicated in the ammonia synthesis block flow diagram of FIG. 3, afeed pretreating section 10 of an ammonia synthesis plant is operable toprepare (e.g., remove undesirable components (e.g., sulfur) from, adjusttemperature and/or pressure of a feed) a carbon-containing feed 5, mostcommonly natural gas, for syngas generation, providing a pretreated feed15. In applications an ammonia synthesis plant of this disclosure doesnot comprise a feed pretreating section. A syngas generation sectioncomposed of a steam reforming section 20 is operable to carry out syngasgeneration by the steam reforming of the feed (e.g., feed 5 orpretreated feed 15) to produce a syngas 25 comprising carbon monoxide(CO) and hydrogen (H₂). In embodiments, air 6 can be introduced into anautothermal reformer of syngas generation section 20. Combustion of theoxygen in this air provides some of the energy needed to heat thesereactors and supply the heat of reaction; the nitrogen in the air iscarried through the process for conversion into ammonia. A shiftconversion or ‘shifting’ section 30 is operable to subject the syngas 25to water gas shifting to provide additional hydrogen via the water gasshift (WGS) reaction of Equation (1):

H₂O+CO→H₂+CO₂,  (1)

and provide shifted reformer product 35. A hydrogen and nitrogenpurification section 40 is operable to produce an ammonia synthesis feedstream (also referred to herein as a purified reformer product) 45comprising purified hydrogen and nitrogen. An ammonia synthesis section50 is operable to produce ammonia from the ammonia synthesis feed 45 andthus provide an ammonia product 55. In embodiments, substantially purenitrogen is introduced just prior to introduction of the ammoniasynthesis feed into ammonia synthesis section 50/150. It is to beunderstood that, in such embodiments, the gas purified in hydrogen andnitrogen purification section 40/140 does not comprise nitrogen.

As mentioned above and depicted in FIG. 3, energy (E) input to or withinthe ammonia synthesis plant or one or more sections or groups of unitsor unit operations thereof (that may conventionally be provided via acarbon based energy (E_(C)) 2A from a carbon based energy source, afossil fuel derived energy (E_(F)) 3A from a fossil fuel-based energysource, or via the use of steam (e.g., steam generated for this purposeusing energy derived from a carbon or fossil fuel based energy source)solely or primarily as a heat or energy transfer medium (S_(HT)) 1), maybe partially or completely replaced by energy from a non-carbon basedenergy (E_(NC)) 2B from a non-carbon based energy source,renewable/non-fossil based energy (E_(NF)) 3B from a renewable energysource, and/or electricity (e.g., electricity and/or renewableelectricity). The carbon based energy (E_(C)) 2A, the fossil fuelderived energy (E_(F)) 3A, or both can be partially or completelyreplaced by electricity. The electricity may be derived from anon-carbon based fuel, a renewable fuel, a renewable energy source, or acombination thereof, in embodiments. A benefit derived via the hereindisclosed system and method may be a reduction in the greenhouse gas(GHG) emissions 4 from the ammonia synthesis plant or process. Inembodiments, energy efficiency is increased by the elimination of fluegas, since the loss of heat contained in the flue gas to the atmosphereis eliminated. The elimination or reduction of the steam system may alsoresult in lower capital and operating costs.

According to this disclosure, when cooling process streams, as much heatas possible should be used to heat other process streams. However, belowa certain temperature, further heat transfer is no longer effective oruseful, and blowers, cooling water, and/or refrigeration (which requirean energy input for heat removal) are utilized. In such embodiments, forexample, heat exchangers, refrigeration units, or a combination thereoffor altering the temperature of process streams may be poweredelectrically. In embodiments, steam is not utilized solely as anintermediate heat and/or energy transfer stream, and the plant orsection(s) thereof do not comprise an elaborate steam system such asconventionally employed for energy transfer. In embodiments, steam isused as a heat transfer fluid and is not used to do mechanical work, forexample to drive a pump or compressor. In embodiments, heating isprovided via resistive heating. In embodiments, heating is provided viainductive heating.

Although not intending to be limited by the examples provided herein, adescription of some of the ways an ammonia synthesis plant can beelectrified according to embodiments of this disclosure will now beprovided with reference to the exemplary ammonia synthesis block flowdiagram of ammonia synthesis plant II of FIG. 4. The steps, sections,groups of units or unit operations described may be present or operatedin any suitable order, one or more of the steps, sections, units, orunit operations may be absent, duplicated, replaced by a different step,section, unit or unit operation, and additional steps, sections, units,or unit operations not described herein may be employed, in variousembodiments. Additionally, although a step (e.g., heating B2) is notedas being in a particular section (e.g., in hydrogen and nitrogenpurification section 40/140), the step could also be considered a partof another section (e.g., ammonia synthesis section 50/150).

As noted hereinabove with reference to the embodiment of FIG. 3, inembodiments, an ammonia synthesis plant comprises a feed pretreatingsection 10/110. Such a feed pretreating section 10/110 can be operableto remove one or more components such as, without limitation, sulfur,from a carbon-containing feed to provide a pretreated feed 15/115. Ifthe carbon-containing feed comprises sulfur, sulfur compounds may beremoved because sulfur deactivates the catalyst(s) used in subsequentsteps. Sulfur removal can utilize catalytic hydrogenation to convertsulfur compounds in the feedstocks to gaseous hydrogen sulfide via theEquation (2):

H₂+RSH→RH+H₂S(gas)  (2).

The gaseous hydrogen sulfide can then be adsorbed and removed by passingit through beds of, for example, zinc oxide, where it is converted tosolid zinc sulfide via the Equation (3):

H₂S+ZnO→ZnS+H₂O  (3).

Feed purification apparatus utilized in feed pretreating section 10 canbe any suitable contaminant/poison removal apparatus known to those ofskill in the art. In embodiments, the pretreating section 10/110 isoperable to provide the feed at a desired operating temperature and/orpressure for the downstream syngas generation or reforming section20/120.

According to embodiments of this disclosure, feed pretreating can beeffected with a reduced usage of non-carbon based energy, the use ofrenewable energy, and/or the use of electricity (e.g., electricity fromrenewable and/or non-renewable source(s)). For example: compressors ofthe pretreating section can be operated with electric motors rather thangas or steam driven turbines, heat input or removal needed in feedpretreating can be electrically provided, or a combination thereof. Inembodiments, pressure reduction is utilized to generate electricity. Inembodiments, feed pretreatment catalysts are regenerated usingelectrical heating and/or electrically-heated gas.

An ammonia synthesis plant according to this disclosure comprises asyngas generation section operable to reform the carbon-containing feedto produce hydrogen and carbon monoxide. The syngas generation sectioncan include steam methane reforming, autothermal reforming, or both. Inembodiments, a syngas generation section 120 comprises a steam methanereformer or bed, an autothermal reforming reactor or bed, and anadiabatic steam methane reforming reactor or bed.

Syngas generation section 20/120 can be operable to effect catalyticsteam reforming of the (e.g., sulfur-free) methane feed to form hydrogenplus carbon monoxide via the reversible and equilibrium limited Equation(4):

CH₄+H₂O⇄CO+3H₂  (4).

The syngas generation section 120 of the embodiment of FIG. 4 comprisessteam methane reforming at 120A, whereby methane in natural gas feed 105and steam in line 111 are combined and then fed to a steam methanereforming furnace where the methane is partially converted to carbonmonoxide and hydrogen via Equation (4). In embodiments, the steammethane reforming reaction occurs over a broad temperature range fromabout 350° C. to 850° C. and at a pressure of from about 25 bar to 50bar. The steam methane reforming reaction is endothermic and the heat ofreaction is conventionally provided by burning methane at the furnaceburners to provide heat input, indicated as Q1. As described furtherhereinbelow, according to embodiments of this disclosure, the heat inputQ1 is provided via a renewable energy source, a non-carbon based energysource, and/or electricity. The renewable energy source can compriseelectricity from a renewable energy source (such as wind or solarenergy).

At autothermal reforming 120B, air 106 is added (e.g., via compressor orcompression section C1) to the partially converted stream indicated at121 and the oxygen in the air combusts with methane to generate carbonoxides, water, and heat. The exit temperature of the autothermalreformer at 120B can be about 1000° C., although some hotter and coolerzones may exist in the reactor. In the embodiment of FIG. 4, theaddition of air in this step provides for the introduction of nitrogen.If autothermal reforming is done such that less than the necessaryamount of nitrogen is supplied in this step (e.g., if purified oxygen isadded in place of air) or if an autothermal reformer is not present,nitrogen will need to be added during a subsequent step of the process;for example, nitrogen obtained from an air separation unit (ASU) couldbe introduced into dry gas stream 144, in embodiments. In the embodimentof FIG. 4, nitrogen from the air introduced at 106 remains in the streamand becomes a raw material for the ammonia synthesis section 150 of theprocess. Impurities such as argon that are introduced with the air inthe autothermal reformer also carry through the process and can beremoved, in embodiments, by a purge.

In the embodiment of FIG. 4, a final step of syngas generation section120 is an optional adiabatic steam methane reforming bed 120C, for whichheat from the combustion provides the heat of reaction. The autothermalreforming product indicated at 122 is subjected to adiabatic steammethane reforming, as indicated at 120C.

Conventionally, a fuel (e.g., natural gas, methane, purge gas from theammonia synthesis section) is burned to provide heat Q1 needed to attaina desired reforming temperature. In embodiments of this disclosure, adesired steam reforming temperature is attained without burning a fuel.In embodiments of this disclosure, a desired steam reforming temperatureis attained without burning a carbon-based fuel. Desirably, no naturalgas or methane is burned as a fuel, as such natural gas or methaneconventionally burned as a fuel can then be utilized as a feed toproduce additional ammonia product according to embodiments of thisdisclosure.

In embodiments, steam reforming can be effected with a reduced usage ofnon-carbon based energy, the use of renewable energy, and/or the use ofelectricity (e.g., electricity from renewable and/or non-renewablesource(s)). For example: compressors of the reforming section (such ascompressor C1) can be operated with an electric motor, anelectricity-driven turbine, and/or a turbine driven byelectrically-produced steam rather than via a gas or steam driventurbine or a turbine driven by steam produced via the combustion of afuel; the heat input Q1 required to attain and maintain a desiredreforming temperature and provide the endothermic heat of reaction (in asteam methane reformer 120A and/or an adiabatic steam methane reformer120C) can be electrically provided; or a combination thereof. Inembodiments, the steam reformer(s) are heated with resistive orinductive heating. In embodiments, the steam reformer(s) are heated bymeans of radiative panels that are heated electrically (e.g., viaresistive heating, inductive heating, ohmic heating, or the like.)

In embodiments, steam for the reforming reaction can be generated withelectrical heating. In embodiments, the steam is generated using anelectrode boiler or a resistive immersion heater. In embodiments,preheating of the feed is effected by the injection of steam that is ata higher temperature than the feed stream to be heated. In embodiments,this steam is superheated electrically. The air 106 introduced to theautothermal reformer can be electrically heated. In embodiments, thesteam methane reforming reactor at 120A is electrically heated to give acontrolled temperature profile such that the extent of reaction isincreased. In embodiments, this controlled profile more closelyapproximates isothermal operation. In embodiments, the feed to theautothermal reformer comprises oxygen, rather than air, and nitrogen isintroduced later in the process, e.g., between steps C2 and B2. Inembodiments, this oxygen and nitrogen are obtained from an airseparation unit (ASU). In embodiments, the air separation unit isoperated using renewable electricity. In embodiments the syngasgeneration section 20/120 does not contain an autothermal reformer, andnitrogen is introduced as a pure nitrogen stream produced in anelectrically powered air separation unit. In embodiments, the syngasexiting a primary reformer may be heated (e.g., via the use ofelectrical energy/heating) to a temperature at which it can be furtherconverted in an adiabatic steam reforming reactor. Nitrogen (e.g. froman electrically powered ASU) may be introduced either before or afterthe adiabatic reformer. In embodiments in which the nitrogen isintroduced before the adiabatic steam reformer, this nitrogen stream maybe preheated (e.g., electrically) so as to provide some or all of theadditional heat required to raise the temperature of the syngas inlet tothe adiabatic reformer.

As noted above, an ammonia synthesis plant of this disclosure cancomprise a shift conversion or ‘shifting’ section 30/130. The shiftconversion section 30/130 can comprise a high temperature shift reactor,a low temperature shift reactor, a first shift reactor, a final shiftreactor, or a combination thereof. The shift conversion section caninclude cooling upstream and/or downstream of the high temperature shiftreactor, the low temperature shift reactor, or both, wherein the heatremoved can be transferred either directly or indirectly to anotherprocess stream.

After the syngas generation is complete, the syngas product stream 125is subjected to water gas shifting in the shift conversion section30/130 to produce additional hydrogen via the water gas shift (WGS)reaction of Equation (1) above. The shifting can be effected via anysuitable methods known in the art, in embodiments, so long as the energyfor the ammonia synthesis plant I/II or the shifting section 30/130 isprovided as detailed herein. For example, shifting can comprise hightemperature shift, low temperature shift, or both, as in the embodimentof FIG. 4. In the embodiment of FIG. 4, the syngas product in syngasproduct stream 125 is partially cooled at first cooling step or unit(s)A1 (with heat removal indicated by Q2) to produce a cooled reformerproduct indicated by stream 131. Cooled syngas stream 131 is introducedinto a high temperature shift reactor(s) at 130A where additionalhydrogen (H₂) is formed by shifting water and carbon monoxide to producecarbon dioxide and additional hydrogen via the water gas shift (WGS)reaction of Equation (1) above to provide a high temperature shiftedstream 132. High temperature shift may be performed at a temperature ofabout 300 to 450° C. and a pressure of about 25 to 50 bar inembodiments.

Shifting section 130 can further comprise cooling of the hightemperature shifted stream 132 in a second cooling step or unit(s) A2(with heat removal indicated by Q3), whereby the stream is cooled toprovide cooled, high temperature shifted stream 133.

Shifting section 130 of the embodiment of FIG. 4 further comprisesfurther completion of the shift reaction in a low temperature shiftreactor indicated at step or unit(s) 130B. The cooled, high temperatureshifted stream 133 can be introduced into a low temperature shiftreactor at 130B. In embodiments, the low temperature shift step at 130Bcan be performed at a temperature of about 200 to 300° C. and/or apressure of about 25 to 50 bar to provide low temperature shifted stream134. Without limitation, an ammonia synthesis plant of this disclosuremay comprise both high temperature shift 130A and low temperature shift130B because low temperature is needed to drive the reaction to nearcompletion, but the reaction proceeds faster at high temperature.

A third cooling step A3 (with heat removal indicated by Q4) can beemployed to reduce the temperature of the low temperature shiftedreformer product 134, and provide a cooled, shifted reformer productstream 135. In embodiments, the cooled, shifted reformer product stream135 has a temperature suitable for feeding to the hydrogen and nitrogenpurification section 40/140. Such a temperature may be between ambienttemperature and 100° C.

According to embodiments of this disclosure, shifting can be effectedwith a reduced usage of non-carbon based energy, the use of renewableenergy, and/or the use of electricity (e.g., electricity from renewableand/or non-renewable source(s)). For example: the heat removal (such asheat removal Q2 for cooling A1 prior to shifting, the heat removal Q3for cooling A2 between a high temperature shift 130A and a lowtemperature shift 130B, the heat removal Q4 for cooling A3 after a lowtemperature shift 130B) required to provide a desired shift temperaturecan be electrically provided, or a combination thereof. In embodiments,heat removal is matched with heat inputs so that recovered thermalenergy is used for heating other process streams. In embodiments, Q2,Q3, and Q4 are used to supply thermal energy to Q1 Q5, and/or Q7, andthe remaining energy is supplied electrically. In embodiments, reactors(for one or more steps, sometimes including reforming) can have atemperature profile imposed by electric heating. In embodiments,thermoelectric devices and/or heat pumps are used to move energy fromQ2, Q3, and/or Q4 to other places where the energy can be utilized.

As noted above, an ammonia synthesis plant of this disclosure cancomprise a hydrogen and nitrogen purification section 40/140. Thehydrogen and nitrogen purification section 40/140 can be operable toremove one or more components (e.g., carbon dioxide, water, carbonmonoxide, or a combination thereof) from the shifted syngas product instream 35/135. The hydrogen and nitrogen purification section 40/140 cancomprise a carbon dioxide removal apparatus, a methanation apparatus, awater condensing/cooling apparatus, heating apparatus, compressionapparatus, or a combination thereof, as described further hereinbelow.

As noted above, the hydrogen and nitrogen purification section 40/140can comprise a carbon dioxide removal apparatus. As noted above, inembodiments, after shifting, the shifted reformer product stream iscooled and much of the steam present in this stream is condensed. In theembodiment of FIG. 4, the shifted reformer product stream 135 is fed toa carbon dioxide removal apparatus 140A to produce a carbondioxide-reduced stream 141. In embodiments, the carbon dioxide removalapparatus utilizes a suitable solvent (typically an amine or bicarbonatesalt solution) to absorb carbon dioxide. The absorbed carbon dioxide isreleased and the solvent regenerated for recycle to the absorber in aCO₂ stripper of the carbon dioxide removal apparatus. In embodiments,the regeneration of the solvent is performed with electric heating(e.g., utilizing an electric reboiler). In embodiments, this electricheating is effected with an immersion heater. In embodiments, the CO₂can be stripped from the solvent by the injection of low-pressure steam,wherein this steam is produced via heat exchange with another processstream and/or by electrical heating of water. In embodiments, thesolvent is an amine solution.

As noted above, the hydrogen and nitrogen purification section 40/140can comprise a methanation apparatus. Due to the nature of the(typically multi-promoted magnetite) catalyst used in the ammoniasynthesis reaction of ammonia synthesis section 50/150 described below,only very low levels of oxygen-containing (especially CO, CO₂ and H₂O)compounds can be tolerated in the ammonia synthesis feed gas stream(s)or purified reformer product in stream 45/145 (e.g., in the hydrogen andnitrogen mixture). In embodiments, after carbon dioxide removal 140A,the carbon dioxide-reduced stream 141 may be heated, as mentionedfurther hereinbelow and indicated at B1 (with heat input indicated atQ5) prior to methanation 140B in a methanator. Methanation is operableto remove residual carbon monoxide and carbon dioxide via reaction withhydrogen to form methane and water according to Equations (5) and (6):

CO+3H₂→CH₄+H₂O  (5)

CO₂+4H₂→CH₄+2H₂O  (6).

An alternative to the use of a methanator is to convert the trace levelsof CO into CO₂ by the addition of a stoichiometric quantity of oxygenfrom an oxygen containing stream and passing this mixed stream over abed of a selective CO oxidation catalyst (e.g., highly dispersed gold).In this way CO can be reacted with O₂ according to Equation (7):

CO+½O₂→CO₂  (7).

When this alternative CO removal process is employed, it should becarried out prior to the CO₂ removal step. An advantage of thisalternative process is that, in contrast to methanation, no hydrogen isconsumed. Suitable oxygen containing streams include air,oxygen-enriched air produced in an air separation plant and pure oxygenproduced in an air separation plant (which may be electrically powered,in embodiments).

As noted above, the hydrogen and nitrogen purification section 40/140can comprise a water removal or “water condensing” apparatus. In theembodiment of FIG. 4, the methanation product stream 143 stream iscooled and the water 147 is condensed out (with heat removal indicatedat Q6) at water condensing A4, to produce a dry gas stream 144. Inembodiments this water removal step may be carried out using desiccantor molecular sieve beds (e.g. 3A molecular sieve) through which thecooled methanator product stream is passed to generate a dry gas streamuntil such time as the molecular sieve bed is saturated, whereupon saidstream is switched to an alternate molecular sieve bed and the nowsaturated molecular sieve bed is dried by passing a heated stream of drygas (e.g., a regeneration gas) through it. Said stream of dry gas maycomprise nitrogen or fuel gas and may be heated to the requiredtemperature (e.g., to approximately 220° C.) using electrical energy, inembodiments.

As noted above, the hydrogen and nitrogen purification section 40/140can comprise compression C2. For example, in the embodiment of FIG. 4,the dry gas stream 144 is introduced to the ammonia synthesis section150 via compression C2 with one or more compressors. Compression C2 canraise the pressure to about 60 to 250 bar, in embodiments.

As noted above, the hydrogen and nitrogen purification section 40/140can comprise heating apparatus. Heating can be provided upstream ofmethanation; downstream of compression and upstream of ammonia synthesissection 150; or both. For example, after carbon dioxide removal 140A,the carbon dioxide-reduced stream 141 may be heated, as mentionedfurther hereinbelow and indicated at B1 (with heat input indicated atQ5) prior to methanation 140B in a methanator. The compressed dry gas inpurified reformer product stream 145 can be heated B2 (with heat inputindicated at Q7) after compression C2 and prior to ammonia synthesis inammonia synthesis section 150. The purified reformer product incompressed, dry gas stream 145 can be heated, for example, to atemperature in the range of from about 100° C. to about 350° C. (instream 146) prior to ammonia synthesis.

According to embodiments of this disclosure, hydrogen and nitrogenpurification can be effected with a reduced usage of non-carbon basedenergy, the use of renewable energy, and/or the use of electricity(e.g., electricity from renewable and/or non-renewable source(s)). Forexample: carbon dioxide removal 140A can be electrified by electrifyingsolvent regeneration. Methanation 140B can be electrified, for example,by electrically heating gas 141 at B1 and/or by electrically heating themethanation reactor at 140B. Hydrogen and nitrogen drying (e.g., at A4)may be electrified, for example, by electrically heating theregeneration gas stream. In embodiments, the heat input Q5 required toattain a desired methanation temperature by heating B1 can beelectrically provided; the heat removal Q6 required to effect watercondensing A4 can be electrically provided; the compressing utilized atC2 can be effected via an electric motor, an electricity-driven turbine,and/or a turbine driven by electrically produced steam rather than agas-driven turbine and/or a steam turbine driven by steam produced fromcombustion of a fuel; the heat input Q7 needed to reach a desiredammonia synthesis temperature at heating B2 can be electricallyprovided; or a combination thereof. In embodiments, heat removal ismatched with heat inputs so that recovered thermal energy is used toheat other process streams. In embodiments, the energy recovered in Q6is applied to energy input Q5, and the balance is supplied electrically.In embodiments, hydrogen obtained from another source is added to theprocess in the hydrogen purification section 40/140. In embodiments,this hydrogen is obtained from a process that uses renewableelectricity. In embodiments, some or all of the nitrogen needed forammonia synthesis is added near the end of the hydrogen purificationsection 40/140 (for example via nitrogen line 266 depicted in FIGS.10-14 and described in Comparative Example 2 and Examples 5-8hereinbelow). In embodiments, hydrogen or nitrogen are compressed and/orheated electrically before being added into the hydrogen purificationsection 40/140.

In embodiments, enough hydrogen is available from outside sources (e.g.,from a steam cracker, from refinery sources, and/or from waterelectrolysis) that the reforming and shift conversion sections are nolonger needed. Nitrogen of the appropriate purity from other sources(e.g., from an air separation unit) is then added to this hydrogen priorto compression C2. Heating B2, ammonia synthesis 150A, cooling A5/A6 andseparation then proceed as described below. In embodiments, all hydrogenis produced using a non-carbon based energy source, a renewable energysource, electricity, and/or renewable electricity. In embodiments, thenitrogen is obtained from an air separation unit powered mostly orentirely by electricity. In embodiments, the compressor of compressionC2, recycle compressor C3, and/or the compressor(s) used forrefrigeration A6 are driven electrically. In embodiments, a majority,60%, 70%, 80%, 90%, or all external energy for heating B2, ammoniasynthesis 150A, cooling A5/A6 and separation is supplied using anon-carbon based energy source, a renewable energy source, electricity,and/or renewable electricity.

In embodiments, the hydrogen and nitrogen stream from which carbondioxide has been removed (e.g., stream 144), may be further purified toreduce or eliminate contamination with methane, for example using apressure swing adsorption (PSA) system, generating a purified hydrogenand nitrogen stream low in methane and a separate methane stream. Inembodiments, said separate methane stream may be recycled to the syngasgeneration section 20/120 whereas the low in methane purified hydrogenand nitrogen stream may be fed to the ammonia synthesis loop. Thisapproach can, in embodiments, reduce the need for loop purging andimprove the overall efficiency of the process.

In embodiments, a PSA type system can be used to remove methane, CO andCO₂ from the hydrogen and nitrogen stream ahead of the ammonia synthesisloop of ammonia synthesis section 50/150, or optionally ahead of amethanator of 140B. In such embodiments, the hydrogen and nitrogenstream can be fed to the synthesis loop whereas the mixed carbon oxidesand methane stream can be further processed to produce relatively pureCO₂ and methane streams. In embodiments, the relatively pure CO₂ andmethane streams can be fed to a urea plant and recycled to the synthesisgas generation sections of the ammonia plant, respectively.

As noted above, an ammonia synthesis plant of this disclosure cancomprise an ammonia synthesis section 50/150. The ammonia synthesissection 50/150 can comprise one or more ammonia synthesis reactors orcatalyst beds for carrying out the ammonia synthesis 150A; coolingapparatus A5/A6 operable to remove heat after each of the one or moreammonia synthesis reactors or catalyst beds; compression apparatus (alsoreferred to herein as a recycle compressor) C3 operable to recyclenitrogen and hydrogen to the one or more ammonia synthesis reactors; apurge gas system 150B operable to purge gas (e.g., methane, argon,nitrogen, and/or CO₂) from the ammonia synthesis section 50/150; or acombination thereof, as described further hereinbelow.

In the ammonia synthesis section 50/150, nitrogen (N₂) and hydrogen (H₂)are reacted to make ammonia (NH₃). In embodiments, to produce thedesired ammonia end-product, the purified hydrogen is catalyticallyreacted with nitrogen to form ammonia according to equilibrium limitedEquation (8):

3H₂+N₂±2NH₃.  (8).

The nitrogen for the ammonia synthesis reaction may already in thepurified syngas generation section product stream 45/145 (e.g., derivedfrom process air at 106 as in the embodiment of FIG. 4), or can be addedto the purified hydrogen stream in alternative embodiments. As notedabove, due to the nature of the (often multi-promoted magnetite)catalyst used in the ammonia synthesis reaction, only very low levels ofoxygen-containing (especially CO, CO₂ and H₂O) compounds can betolerated in the synthesis gas (e.g., the hydrogen and nitrogenmixture). In the embodiments just mentioned wherein nitrogen is addedafter hydrogen purification 40/140, relatively pure nitrogen can beobtained by air separation. Additional oxygen removal may be required,in embodiments. One advantage of supplying pure nitrogen produced usingan air separation process is that argon and other impurities can also beremoved from the nitrogen and, hence, the hydrogen and nitrogen streamfeed into the ammonia synthesis section 50/150 can comprise a reducedamount or substantially no such inert materials. This can reduce theneed for purging of the synthesis loop typically required to prevent thebuild-up of non-reactive gases, and increase the overall efficiency ofthe process.

As noted above, the ammonia synthesis section 50/150 can comprise one ormore ammonia synthesis reactor(s) and/or catalyst bed(s). The ammoniasynthesis reaction can be carried out in one or more ammonia synthesisreactors or catalyst beds of ammonia synthesis section 50/150. Theammonia synthesis reaction of Equation (8) is exothermic and conversionis equilibrium limited. In embodiments, the ammonia synthesis reactionis carried out at about 200 to 500° C. In embodiments, the reaction iscarried out over a series of (e.g., three) catalyst beds/reactors andheat is removed in between the beds (heat removal from the ammoniasynthesis section 50/150 between and/or after the ammonia synthesisreactor(s)/catalyst bed(s), indicated at Q8 in FIG. 4). Without wishingto be limited by theory, the heat removal can be utilized to limit thetemperature rise and thus increase the extent of reaction.

As noted above, in embodiments, the ammonia synthesis section 50/150comprises cooling apparatus operable to remove heat after each of theone or more ammonia synthesis reactors or catalyst beds and to enableseparation of ammonia from the effluent gas stream obtained from theammonia synthesis reactor(s). This cooling may occur in one or moresteps. In embodiments, the post-ammonia-synthesis cooling comprises twosteps: a first step comprising thermal cooling (where heat can beextracted) and a second step, which requires an energy input (primarilyrefrigeration). In a first post-ammonia-synthesis cooling, as indicatedat A5 (with energy removal indicated at Q8), the cooling is operated toextract heat and/or energy from ammonia in line 151 that can be usedelsewhere in the process (e.g., via heat exchange). In a secondpost-ammonia-synthesis cooling, as indicated at A6, energy input (e.g.,work in driving a compressor) is required to further cool the productstream 151′ from the first cooling A5 such that ammonia is condensed andremoved via ammonia product stream 155. In this second cooling, theproduct stream can be cooled and then chilled to a range of about −10 toabout 5° C. at a high pressure (e.g. close to ammonia synthesis looppressure) such that the ammonia is condensed and removed as a liquid.The remaining vapor, containing a majority of the unreacted hydrogen andnitrogen and a minority of the ammonia, is recycled via line 152 andrecycle compressor C3 to the ammonia synthesis loop (e.g., via recyclestream 153), whereas the liquid stream (e.g., ammonia stream 155),containing the majority of the ammonia and a minority of the unconvertedhydrogen and nitrogen, can be further chilled and depressurized forfurther purification thereof, if desired, and the ammonia productstored, sold, or etc.

As noted above, in embodiments, the ammonia synthesis section 50/150comprises compression apparatus (also referred to herein as a recyclecompressor) C3 operable to recycle nitrogen and hydrogen to the one ormore ammonia synthesis reactors. In the embodiment of FIG. 4, theunreacted nitrogen and hydrogen are compressed via recycle compressorC3, and recycled back to ammonia synthesis 150A via recycle stream 153.In embodiments, the compression C2 of the dried gas stream 144 and thecompression C3 of recycle stream 153 may be combined in a singlecompressor of one or more stages.

As noted above, in embodiments, the ammonia synthesis section 50/150comprises a purge gas system operable to purge gas (e.g., methane,nitrogen (N₂), hydrogen (H₂), argon (Ar) and/or impurities) from theammonia synthesis section 50/150. In embodiments, to handle build-up ofresidual methane and inerts in the recycle gas in recycle stream 153,methane and inerts are purged from the recycle gas via a purge gassystem 150B. In the embodiment of FIG. 4, purge gas in line 154 enterspurge gas system 150B, and is removed from the ammonia synthesis plantvia purge line 105′. The methane purge may be introduced into feedpretreating section 10/110 and/or syngas generation section 20/120 as acomponent of the reformer feed. Purge gas system 150B can involve heatremoval, as indicated at Q9. In embodiments this purge gas may beprocessed, for example using a PSA, to separate it into two or moredifferent streams comprising specific compounds or groups of compounds.In embodiments, methane and/or inert gases (e.g., Ar) are separated fromthe purge gas, such that the methane may be introduced as a feed to thesyngas generation section 20/120 whilst some or the majority of theinert gases (e.g. Ar) present in the purge gas stream may be excludedfrom the process. In embodiments this purge gas may be processed, forexample using a PSA, to separate a stream of purified hydrogen. Inembodiments, this hydrogen stream may be recycled to the ammoniasynthesis reactors, combusted to produce hot steam for steam methanereforming, exported as a valuable byproduct, and/or used to generateelectricity. In embodiments, the separated hydrogen may be stored whenelectricity is readily available and used when electricity is notreadily available and/or is not available at a desirable price. Inembodiments, nitrogen separated from the purge gas is recycled (e.g.,added to dry gas stream 144) for conversion to ammonia.

According to embodiments of this disclosure, ammonia synthesis 150 canbe effected with a reduced usage of non-carbon based energy, the use ofrenewable energy, and/or the use of electricity (e.g., electricity fromrenewable and/or non-renewable source(s)). In embodiments, the heatremoval Q8 required to attain a desired ammonia synthesis temperaturewithin or downstream of one or more ammonia synthesis reactors (e.g.,via cooling A5) is transferred to other streams via heat exchange, orthis energy is otherwise utilized by conversion to electricity; thecompressing utilized at recycle compressor C3 can be effected via anelectric motor, an electricity-driven turbine, and/or a turbine drivenby electrically produced steam rather than via a gas-driven turbineand/or a turbine driven by steam produced via combustion of a fuel; theheat removal Q9 needed by purge gas system 150B can be electricallyprovided; or a combination thereof. In embodiments, thecooling/refrigeration system for obtaining product ammonia (A6) isdriven such that energy input is provided by electricity. Inembodiments, the higher efficiency of electrically-driven compressorsutilized at C2 and C3 allow for a higher than normal pressure in theammonia synthesis reactor at 150A to be achieved economically andresults in a higher per-pass yield of ammonia. In embodiments, thishigher pressure allows for the reactor temperature to be lowered andresults in a higher per-pass yield of ammonia. In embodiments, thehigher efficiency of the electrically-driven compressors in therefrigeration system at A6 allows for economical separation of ammoniaat a lower temperature, enabling a more complete separation. Inembodiments, a combination of higher pressure, lower temperature, and/orhigher yield allow ammonia to be condensed against cooling water ratherthan a colder refrigerant at A6.

In embodiments, a majority, greater than 20, 30, 40, 50, 60, 70, 80, or90%, or substantially all of the net heat input or removal (Q1, Q2, Q3,Q4, Q5, Q6, Q7, Q8, and/or Q9) needed within the ammonia synthesis plantis provided from a non-carbon based energy source, from a renewableenergy source, such as renewable electricity, and/or from electricity(e.g., electricity from renewable and/or non-renewable source(s)).

In embodiments, a majority, greater than 20, 30, 40, 50, 60, 70, 80, or90%, or substantially all of the energy needed for compression (e.g., atair compressor C1, dry gas stream compression C2, and/or recyclecompressor C3) within the ammonia synthesis plant is provided from anon-carbon based energy source, from a renewable energy source, such asrenewable electricity, and/or from electricity (e.g., electricity fromrenewable and/or non-renewable source(s)). For example, an electricmotor, an electrically-driven turbine, and/or a turbine driven by steamproduced electrically may be utilized to provide compression throughoutthe ammonia synthesis plant or one or more sections thereof. Inembodiments, a majority, greater than 20, 30, 40, 50, 60, 70, 80, or90%, or substantially all of the compressors are replaced by or utilizean electric motor, an electrically-driven turbine, and/or a turbinedriven by steam produced electrically.

In embodiments, electricity is utilized to produce slightly colder(e.g., 2, 5, 10 or 15° C. colder) cooling water than conventional. Inembodiments, electricity is utilized to supply the energy needed for therefrigeration system.

In embodiments, electricity can be used to provide the motive force forfluids. For example, electricity can be used to power pumps to moveand/or pressurize liquids, and/or to power air blowers and/or fans. Inembodiments, a fraction, a majority, or all (e.g., 20, 30, 40, 50, 60,70, 80, 90, or 100%) of the number of pumps utilized in the ammoniasynthesis plant are electrified.

As noted above, when utilizing electricity from a renewable source thathas a potentially or known intermittent supply (e.g., an intermittentenergy source or IES), various steps can be taken to maintain operationof the ammonia synthesis plant, according to embodiments of thisdisclosure. Such handling of an IES can be as described in U.S.Provisional Patent Application Nos. 62/792,636 and 62/792,637, entitledUse of Intermittent Energy in the Production of Chemicals, which arebeing filed on Jan. 15, 2019, the disclosure of each of which is herebyincorporated herein for purposes not contrary to this disclosure. Forexample, in embodiments, compressed hydrogen is stored for intermittencyof electric supply. Alternatively or additionally, recovered hydrogenseparated from the purge gas can be pressurized and stored whenelectricity is available and used to generate electricity using a fuelcell during times of low electric supply. Alternatively or additionally,one or more cryogenic liquids can be stored for intermittency ofelectric supply. Alternatively or additionally, heat can be stored forintermittency of electric supply.

In embodiments, when a methane steam reformer is utilized in syngasgeneration section 20/120, heat may be stored in the insulating materiallining the internals of the reforming furnace, thereby increasing theheat storage capacity of the furnace such that temporary loses ofelectrical power to the heating elements therein would result in only asmall drop in the temperature of the reforming tubes which are heatedlargely through radiation from the surface of surrounding insulatingmaterial. Alternatively or additionally, batteries can be kept forintermittency of electric supply. Backup power for key components may beprovided; non-renewable electricity may be utilized as a back-up forintermittent renewable electricity. For example, such backup power maybe produced via apparatus driven by compressed gas or a flywheel.Alternatively or additionally, natural gas feed, hydrogen, or nitrogencan be stored for intermittency of electric supply. Alternatively oradditionally, stored compressed gases can be used to generateelectricity as they are depressurized. Alternatively or additionally,cooled ammonia product can be stored for use as a refrigerant forintermittency of electric supply.

Electrification of the ammonia synthesis plant of this disclosure can beprovided via an electricity supply that can be high voltage or lowvoltage. The electric devices can be operable or operated on alternating(single or multiphase) or direct current.

In embodiments, steam generated by the combustion of fuels or producedsolely for heat and/or energy transfer is not utilized in an ammoniasynthesis system and method of this disclosure (e.g., in the pretreatingsection 10/110, the syngas generation/reforming section 20/120, theshift conversion section 30/130, the hydrogen and/or nitrogenpurification section 40/140, and/or the product purification section50/150). In this manner, an ammonia synthesis plant according to thisdisclosure can be operated, in embodiments, without an elaborate steamheat and/or energy transfer system (which may be conventionally utilizedin an ammonia synthesis plant). In some applications, for example wheresteam is utilized within a reactor as a feed component and/or diluent,such steam may be produced via heat transfer with a process streamwithin the ammonia synthesis plant and/or may be produced electrically.In embodiments, steam generated via heat transfer with a process streammay be superheated using electricity. In embodiments, steam is notutilized throughout the ammonia synthesis plant as a commodity orutility. In embodiments, an ammonia synthesis plant of this disclosureis essentially steam-free, or utilizes substantially less steam (e.g.,uses at least 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 volume percent(vol %) less steam) than a conventional plant for producing ammonia. Forexample, a conventional plant for producing ammonia may utilize steamproduction for reboilers of distillation columns of the feed pretreatingsection 10/110 and/or the hydrogen and/or nitrogen purification section40/140, may utilize steam production to drive steam turbines forcompressing process and/or recycle streams, or may utilize steamproduction to drive steam turbines for refrigeration. In embodiments,steam is not produced for these operations in an ammonia plant accordingto this disclosure, or substantially less steam is produced (e.g., atleast 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 volume percent (vol %)less steam). In embodiments, steam is used as a heat transfer fluid, butis not used to do mechanical work (e.g., to drive a compressor or pump.)In embodiments, the steam generated for these operations is primarily(e.g., of the total steam utilized, the greatest percentage iselectrically produced), mainly (e.g., greater than 50% of the steam iselectrically produced) or substantially all electrically produced. Inembodiments, the steam utilized as a reactant or diluent is primarily(e.g., of the total steam utilized, the greatest percentage iselectrically produced), mainly (e.g., greater than 50% of the steam iselectrically produced) or substantially all electrically produced.

In embodiments, in an ammonia synthesis plant or process of thisdisclosure, more energy is utilized directly ‘as-is’, for example,utilizing heat from a hot product effluent stream to heat a feed stream,rather than being transformed, e.g., via the generation of steam and theconversion of the thermal energy to mechanical energy via a steamturbine. According to embodiments of this disclosure, the use of energydirectly can increase the energy efficiency of the ammonia synthesisplant, for example by reducing energy efficiency losses that occur whenheat is converted to mechanical energy.

As energy consumption is a large fraction of the operating costs of atraditional ammonia synthesis plant, increasing energy efficiency (e.g.,via electrification) as per this disclosure and/or utilizing natural gasconventionally burned to provide heat for syngas generation (e.g. byreforming) and/or burned for compression (e.g., burned to produce steamfor a steam turbine or burned for a gas turbine) to produce additionalammonia may provide economic advantages over a conventional ammoniasynthesis plant. Concomitantly, the reduction of the burning of fossilfuels (e.g., natural gas, methane) as a fuel enabled via this disclosureprovides for reduced greenhouse gas (GHG) emissions relative to aconventional ammonia synthesis plant in which hydrocarbons are burned asfuel. In embodiments, GHG emissions resulting from the provision ofenergy for the process (e.g., carbon dioxide emissions) are reduced byat least 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% relative to aconventional ammonia synthesis plant in which hydrocarbons are burned asfuel. In embodiments of this disclosure, the amount of CO₂ produced perton of ammonia produced is reduced to less than 1.6, 1.5, 1.4, 1.3, 1.2,1.1, or 1.0 tons CO₂ per ton ammonia. In embodiments, aspects of thisdisclosure can lead to an increase in carbon efficiency of a process,i.e. to a fraction of carbon consumed in the process that reappears as auseful product, and/or a reduced specific energy consumption (e.g., theenergy utilized to synthesize a quantity of chemical product).

Conventionally, the energy required for unit operations in chemicalprocesses is generally provided by the burning of fossil fuels,especially natural gas. Herein-disclosed are systems and methods bywhich this energy input can be reduced or replaced, in embodiments, withnon-carbon based energy, renewable energy, such as renewableelectricity, and/or by electricity from any source (e.g., renewableand/or non-renewable), such that energy efficiency is improved (e.g.,energy losses are reduced). In embodiments, energy efficiency (e.g.,reduced energy losses) is increased by a decrease in or elimination ofthe use of steam to do mechanical work. In embodiments, the energyefficiency of the process is increased such that the specific energyconsumption (the total net energy input, including fuel and electricity,but not including any contribution of the heat of reaction, feed, orbyproduct credits, to the process divided by the production rate) isless than 12, 11, 10, 9, 8, or 7 GJ/ton of ammonia produced, where thespecific energy consumption is calculated using the higher heating valueof the fuel. In embodiments, the total amount of methane and/or naturalgas used as feed and fuel is less than 0.65, 0.60, 0.55, 0.50, 0.45, or0.40 tons per ton of ammonia produced. In embodiments, the total amountof methane and/or natural gas used as fuel is less than 0.20, 0.15,0.10, 0.05, or 0 tons per ton of ammonia produced. The herein-discloseduse of non-carbon based energy, renewable energy, and/or electricity inthe production of chemicals, such as the production of ammonia via steammethane reforming, increases energy efficiency of and/or decreasesand/or eliminates carbon dioxide emissions from and fossil fuelconsumption within the ammonia synthesis process.

EXAMPLES

The embodiments having been generally described, the following examplesare given as particular embodiments of the disclosure and to demonstratethe practice and advantages thereof. It is understood that the examplesare given by way of illustration and are not intended to limit thespecification or the claims in any manner.

Comparative Example 1: Conventional Ammonia Synthesis with Primary andSecondary (Autothermal) Reforming

A process simulation was performed to determine the heat and mass flowsfor a typical process III for the production of ammonia. The processsimulation utilized in this Comparative Example 1 was made using AspenPlus®. It does not represent a specific operating plant, but it isrepresentative of a typical plant as described hereinbelow withreference to FIG. 5; the design parameters were taken from knowledge ofspecific plants, as well as literature information on typical processoperations. Although variations will be obvious to one skilled in theart, this Comparative Example 1 represents a typical process that can beused as a basis for comparing the effects of electrificationmodifications according to embodiments of this disclosure.

Process III of Comparative Example 1 utilizes primary and secondary(autothermal) reforming (i.e., ATR) and is configured to produce 125metric tons per hour of ammonia. If operated for a typical 8000 hours ina year, this would result in the production of one million tons ofammonia, although variations in downtime due to upsets and maintenancecould increase or reduce this output. This size is typical of largeammonia plants being built today.

As shown in FIG. 5 (which has been simplified to show only the essentialfeatures of the process of this Comparative Example 1), 59 metric tonsper hour (t/hr) of pure methane feed 205 are fed to the process; thepretreatment of this methane feed to remove sulfur and other harmfulcomponents was not included in the model and is not shown in FIG. 5. Anamount of 194 t/hr water 211 is vaporized and mixed with the methanefeed. The resulting feed 215 is further preheated and fed to primaryreformer 220A at approximately 620° C. and 690 psia, where CO, CO₂, andH₂ are produced. Energy Q1 is supplied to primary reformer 220A by anatural gas fired furnace, which supplies the heat of reaction andfurther heats the gases; the firing of this furnace also results inenergy input Q2, which is transferred in the convection section topreheat the feed water/methane mixture 215, and energy loss Q5, which isthe energy lost in the flue gas. The product 221 from primary reformer220A is combined with 149 t/hr preheated air feed 206 and fed tosecondary autothermal reformer 220B where further reaction occurs,producing more CO, CO₂, and H₂. The energy for secondary reformer 220Bis supplied by the oxidation of methane, CO, and H₂ that occurs in thesecondary reformer itself. The product 222 from secondary reformer 220Bis cooled (e.g., at cooling A1) to approximately 320° C. and passedthrough two water gas shift reactors 230, where additional H₂ and CO₂are formed. The product stream 234 from the water gas shift reactors 230is further cooled (e.g., at cooling A2/A3; as utilized herein, A2/A3means ‘A2 and/or A3’) and then purified in CO₂ removal section 240A,where 154 t/hr CO₂ is removed by amine absorption. To release absorbedCO₂ and regenerate the amine solution, a significant amount of energy isrequired. Some of this energy is obtained by heat exchange with thecooling gas streams from the secondary reformer 220B and the water gasshift reactors 230, but additional energy Q3 must be supplied; thisenergy is obtained from auxiliary boiler 260 via the production and useof medium pressure steam 262 from boiler feed water (BFW) 261. Thepurified product stream 241 from CO₂ removal section 240A is heated toapproximately 290° C. and fed to methanation unit 240B, where theremaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) are removed. Theresulting gas stream 243 is cooled and dried at A4 and then theresulting stream 244 is combined with recycle gas 253 and compressed insynthesis loop compressor(s) C2/C3 (which can be a single compressor, inembodiments; as utilized herein, C2/C3 means ‘C2 and/or C3’) to 3095psia; the energy W2 for this compression is supplied by high pressuresteam 263 obtained from auxiliary boiler 260. The combined andcompressed gas stream 245 is preheated to approximately 450° C. and sentto a series of three ammonia synthesis reactors 250A in series withinterstage cooling; per-pass conversion of nitrogen is 30%. Theammonia-containing product stream 251 is first cooled at A5, allowingfor heat recovery for use in heating other process streams, then cooledagain with air and cooling water, and finally cooled to −34° C. usingrefrigeration at A6 so that 125 t/hr liquid ammonia product 255 may berecovered. The energy (e.g., to provide work W3) for refrigerationsection at A6 is supplied by high pressure steam 263 obtained fromauxiliary boiler 260. After ammonia recovery, a 17 t/hr purge 205′ istaken from the remaining gases to allow for removal of impurities; thecomposition of this purge stream is approximately 12 weight % CH₄, 11weight % H₂, 75 weight % N₂, and 2% weight % NH₃. The remainder of thegas stream 253 is then recycled back to synthesis loop compressor(s)C2/C3.

There are four major energy consumers in the conventional process III ofthis Comparative Example 1: (1) regeneration of the amine solution inCO₂ removal 240A, (2) power (e.g., to provide work W1, W2, W3) to drivethe three large compressors via compressor turbines 265 including aircompressor C1, synthesis loop compressor(s) C2/C3, and refrigerationcompressor at A6, (3) heating to raise the temperature of the feed gasesand provide the heat of reaction for the primary reformer 220A, and (4)preheating of the feed (e.g., at heating B2) before the first ammoniasynthesis reactor of 250A. As is common, very little electricity isconsumed, primarily for some smaller pumps. Some of the energy requiredfor these operations can be obtained by heat exchange with streams thatare being cooled (for example, much of the heat required to preheat themethanation reactor feed (e.g., at heating B1) can be obtained from heatremoved when cooling at A4 the product gases 243 from the same reactor),but the rest must be supplied externally and is conventionally generatedby burning fuel. In Comparative Example 1, external energy is suppliedin two places: the primary reformer furnace of primary reformer 220A,and the auxiliary boiler 260. The primary reformer furnace consumes 7.3t/hr of natural gas with a contained chemical energy (high-heatingvalue, or HHV) of 111 MW. Auxiliary boiler 260 consumes 40.5 t/hr ofnatural gas with a contained chemical energy of 617 MW. In addition,although some of the reactions are endothermic (e.g., steam reforming),the net set of reactions for Comparative Example 1 is exothermic andgenerates roughly 70 MW of energy that can be used elsewhere. How tomost efficiently allocate this energy to the various consumers of energyin the process with the highest efficiency is an engineering problemthat can be addressed by one of skill in the art upon reading thisdisclosure via careful matching of temperatures, types of energy, andenergy content. Energy can be transferred directly via heat exchange orit can be converted to steam that can either be used for heat exchangeor to do mechanical work, such as to drive a compressor. In ComparativeExample 1 a strategy was utilized that maximizes heat exchange betweenthe various process streams; assuming that available heat can be movedefficiently from where it is available to where it is needed at acorresponding temperature. This represents a maximal heat integrationstrategy and minimizes external energy inputs, but other arrangementsare possible, as will be obvious to one skilled in the art. The use ofcombustion to supply some of the external energy input needed for theprocess comes with a concomitant disadvantage—the stack or flue gas fromthese furnaces and boilers contains energy that cannot be usefullyrecovered because of its low temperature and difficulties in condensingwater. For example, in the process of Comparative Example 1, this wastedenergy amounts to 147 MW. Energy is also lost in several process stepswhere streams are cooled but the heat cannot be usefully recovered, forexample in the final cooling of the product stream from ammoniasynthesis reactor at 250A.

Table 2 shows energy use values for the process of ComparativeExample 1. As seen in Table 2, an amount of 728 MW of energy is suppliedthrough the combustion of natural gas in the reformer furnace of primaryreformer 220A and the auxiliary boiler 260. An additional 70 MW isobtained as the net exothermic heat of reaction. The total net energyinput to the process is 798 MW, although a large amount (>400 MW) ofenergy is also transferred internally from the cooling of hot productstreams to the heating of feed streams. Of the 111 MW consumed in theprimary reformer furnace at 220A, the radiant section is used to provide57 MW to further heat the gases and supply the heat of reaction; anadditional 31 MW is transferred in the convection section to preheat thefeed water/methane mixture 215. The remaining 23 MW is lost to theatmosphere in the flue gas. An amount of 617 MW is supplied to theauxiliary boiler 260, of which 68 MW is used to supply heat for CO₂removal at 240A and 424 MW provides the power for the three largecompressors, air compressor C1, synthesis loop compressor(s) C2/C3, andthe refrigeration compressor at A6; 124 MW is lost to the atmosphere inthe flue gas. In total, 147 MW, or 18% of the net external energysupplied, is lost in the flue gas from the reformer furnace at primaryreformer 220A and auxiliary boiler 260.

As further seen in the data in Table 2, the total fuel gas consumptionis 382,000 tons per year. The combustion of this fuel results in theatmospheric emissions 1.05 million tons of CO₂ annually. An additional1.23 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 2.28 million tons per year. Specificenergy consumption including the fuel as well as the heat of reaction is22.9 GJ per ton of ammonia produced; specific energy consumptioncalculated only on the fuel inputs is 20.9 GJ per ton of ammoniaproduced. An amount of 40% of the total supplied energy (318 MW out of798 MW) is lost due to inefficiencies in the conversion of steam tomechanical work; another 18% (147 MW) of the total supplied energy islost to the atmosphere from the stack gas.

Example 1: Primary and Secondary Reforming with Electric Compressors

Example 1 is a partial electrification process IV as per an embodimentof this disclosure of the ammonia synthesis process described inComparative Example 1. In process IV, partial electrification isprovided by electric compressors. The key elements of this electrifiedplant or process IV are shown in FIG. 6; except for the provision of theenergy, the process is essentially the same as in Comparative Example 1.An amount of 59 metric tons per hour (t/hr) of methane feed 205 is fedto the process; the pretreatment of this methane feed to remove sulfurand other harmful components was not included in the model and is notshown in FIG. 6. An amount of 194 t/hr water 211 is vaporized and mixedwith the methane feed. The resulting feed 215 is further preheated andfed to primary reformer 220A at approximately 620° C. and 690 psia,where CO, CO₂, and H₂ are produced. Energy Q1 is supplied to primaryreformer 220A by a natural gas fired furnace, which supplies the heat ofreaction and further heats the gases; the firing of this furnace alsoresults in energy input Q2, which is transferred in the convectionsection to preheat the feed water/methane mixture 215, and energy lossQ5, which is the energy lost in the flue gas. The product 221 fromprimary reformer 220A is combined with 149 t/hr preheated air feed 206and fed to secondary autothermal reformer 220B where further reactionoccurs, producing more CO, CO₂, and H₂. The energy for secondaryreformer 220B is supplied by the oxidation of methane, CO, and H₂ thatoccurs in the reformer. The product 222 from secondary reformer 220B iscooled (e.g., at cooling A1) to approximately 320° C. and passed throughtwo water gas shift reactors 230, where additional H₂ and CO₂ areformed. The product stream 234 from the water gas shift reactors 230 isfurther cooled (e.g., at cooling A2/A3) and then purified in CO₂ removalsection 240A, where 154 t/hr CO₂ is removed by amine absorption. Torelease absorbed CO₂ and regenerate the amine solution, a significantamount of energy is required. Some of this energy is obtained by heatexchange with the cooling gas streams from the secondary reformer 220Band the water gas shift reactors 230, but additional energy Q3 must besupplied; this energy is obtained from auxiliary boiler 260 via theproduction and use of medium pressure steam 262 from BFW 261. Thepurified product stream from CO₂ removal section 240A is heated toapproximately 290° C. and fed to methanation unit 240B, where theremaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) are removed. Afterfurther cooling and drying at A4 of methanation product 243, theresulting gas stream 244 is combined with recycle gas 253 and compressedin synthesis loop compressor(s) C2/C3 to 3095 psia; the energy (e.g., toprovide work W2) for this compression is supplied by electricity. Thecombined and compressed gas stream 245 is preheated to approximately450° C. and sent to a series of three ammonia synthesis reactors 250A inseries with interstage cooling; per-pass conversion of nitrogen is 30%.The ammonia-containing product stream 251 is first cooled at A5,allowing for heat recovery for use in heating other process streams,then cooled again with air and cooling water, and finally cooled to −34°C. using refrigeration at A6 so that 125 t/hr liquid ammonia product 255may be recovered. The energy (e.g., for work W3) for refrigerationsection at A6 is supplied by renewable electricity. After ammoniarecovery, a 17 t/hr purge 205′ is taken from the remaining gases toallow for removal of impurities; the composition of this purge stream isapproximately 12 weight % CH₄, 11 weight % H₂, 75 weight % N₂, and 2%weight % NH₃. The remainder of the gas stream 253 is then recycled backto synthesis loop compressor(s) C2/C3.

There are four major energy consumers in the partially electrifiedprocess IV of this Example 1: (1) regeneration of the amine solution inCO₂ removal 240A, (2) power (e.g., for work W1, W2, W3) to drive thethree large compressors, air compressor C1, synthesis loop compressor(s)C2/C3, and refrigeration compressor at A6, (3) heating to raise thetemperature of the feed gases (e.g., at 110) and provide the heat ofreaction for the primary reformer 220A, and (4) preheating of the feed(e.g., at heating B2) before the first ammonia synthesis reactor at250A. Smaller amounts of energy are used for a variety of otherpurposes. Some of the energy required for these operations can beobtained by heat exchange with streams that are being cooled (forexample, much of the heat required to preheat the methanation reactorfeed (e.g., at heating B1) can be obtained from heat removed whencooling at A4 the product gases 243 from the same reactor), but the restmust be supplied externally. In Example 1, external energy is suppliedin three places: the primary reformer furnace at 220A, the auxiliaryboiler 260, and renewable electricity used to power the three largecompressors (e.g., C1, C2/C3, and a refrigeration compressor at A6). Theprimary reformer furnace at 220A consumes 7.3 t/hr of natural gas with acontained chemical energy (high-heating value, or HHV) of 111 MW.Auxiliary boiler 260 consumes 5.6 t/hr of natural gas with a containedchemical energy of 85 MW. An amount of 114 MW of electricity is suppliedto three large compressors; at an efficiency of 93%, this performs thesame work that required 424 MW of high pressure steam 263 in ComparativeExample 1. In addition, although some of the reactions are endothermic(e.g., steam reforming), the net set of reactions for Example 1 isexothermic and generates roughly 70 MW of energy that can be usedelsewhere. How to most efficiently allocate this energy to the variousconsumers of energy in the process with the highest efficiency is anengineering problem that can be addressed by one of skill in the artupon reading this disclosure via careful matching of temperatures, typesof energy, and energy content. Energy can be transferred directly viaheat exchange or it can be converted to steam that can either be usedfor heat exchange or to do mechanical work, such as to drive acompressor. In Example 1 a strategy was utilized that maximizes heatexchange between the various process streams; assuming that availableheat can be moved efficiently from where it is available to where it isneeded at a corresponding temperature. This represents a maximal heatintegration strategy and minimizes external energy inputs, but otherarrangements are possible, as will be obvious to one skilled in the art.The use of combustion to supply some of the external energy input neededfor the process comes with a concomitant disadvantage—the stack or fluegas from these furnaces and boilers contains energy that cannot beusefully recovered because of its low temperature and difficulties incondensing water. In the process of Example 1, this wasted energyamounts to only 40 MW, a reduction of 73% over Comparative Example 1.Energy is also lost in several process steps where streams are cooledbut the heat cannot be usefully recovered, for example in the finalcooling of the product stream from ammonia synthesis reactor at 250A.

Table 2 shows energy use values for the process of Example 1. As seen inTable 2, an amount of 196 MW of energy is supplied through thecombustion of natural gas in the reformer furnace of primary reformer220A and the auxiliary boiler 260, a reduction of 73% over ComparativeExample 1. An amount of 114 MW of renewable electricity is supplied, andan additional 70 MW is obtained as the net exothermic heat of reaction.The total net energy input to the process is 380 MW, although a largeamount (>400 MW) of energy is also transferred internally from thecooling of hot product streams to the heating of feed streams. Of the111 MW consumed in the primary reformer furnace at 220A, the radiantsection is used to provide 57 MW to further heat the gases and supplythe heat of reaction; an additional 31 MW is transferred in theconvection section to preheat the feed water/methane mixture 215. Theremaining 23 MW is lost to the atmosphere in the flue gas. An amount of85 MW is supplied to the auxiliary boiler 260, of which 68 MW is used tosupply heat for CO₂ removal at 240A and 17 MW is lost to the atmospherein the flue gas. In total, 40 MW, or 10.5% of the net external energy(e.g., energy conventionally provided via burning of a fuel) supplied,is lost in the flue gas from the reformer furnace at 220A and auxiliaryboiler 260.

As further seen in the data in Table 2, total fuel gas consumption is103,000 tons per year. The combustion of this fuel results in theatmospheric emissions 0.28 million tons of CO₂ annually. An additional1.23 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 1.51 million tons per year, a decrease of33% over Comparative Example 1. Specific energy consumption, includingthe fuel, electricity, and heat of reaction, is 10.9 GJ per ton ofammonia produced; specific energy consumption calculated only on thefuel and electricity inputs is 8.9 GJ per ton of ammonia produced. Anamount of 10.5% of the total supplied energy is lost in the stack gasand none is lost due to inefficiencies in the conversion of steam tomechanical work, in contrast to Comparative Example 1 where 18% and 40%,respectively, of the energy was lost in these ways.

Example 2: Primary and Secondary Reforming with Electric Compressors andElectric Furnace

Example 2 is a further partial electrification process V as per anembodiment of this disclosure of the ammonia synthesis process describedin Comparative Example 1. In process V, partial electrification isprovided by an electric furnace in addition to the electric compressorsof Example 1. The key elements of this electrified plant/process V areshown in FIG. 7; except for the provision of the energy, the process isessentially the same as in Comparative Example 1. An amount of 59 metrictons per hour (t/hr) of methane feed 205 is fed to the process; thepretreatment of this methane feed to remove sulfur and other harmfulcomponents was not included in the model and is not shown in FIG. 7. Anamount of 194 t/hr water 211 is vaporized and mixed with the methanefeed. The resulting feed 215 is further preheated and fed to primaryreformer 220A at approximately 620° C. and 690 psia, where CO, CO₂, andH₂ are produced. Energy Q1 is supplied to primary reformer 220A byelectric heating, which provides the heat of reaction and further heatsthe gases. The product 221 from primary reformer 220A is combined with149 t/hr preheated air feed 206 and fed to secondary autothermalreformer 220B where further reaction occurs, producing more CO, CO₂, andH₂. The energy for secondary reformer 220B is supplied by the oxidationof methane, CO, and H₂ that occurs in the secondary reformer of 220B.The product from secondary reformer 220B is cooled (e.g., at cooling A1)to approximately 320° C. and passed through two water gas shift reactors230, where additional H₂ and CO₂ are formed. The product stream 234 fromthe water gas shift reactors 230 is further cooled (e.g., at cooling A3)and then purified in CO₂ removal section 240A, where 154 t/hr CO₂ isremoved by amine absorption. To release absorbed CO₂ and regenerate theamine solution, a significant amount of energy is required. Some of thisenergy is obtained by heat exchange with the cooling gas streams fromthe secondary reformer 220B and the water gas shift reactors 230, butadditional energy Q3 must be supplied; this energy is obtained fromauxiliary boiler 260 via the production and use of medium pressure steam262. The purified product stream 241 from CO₂ removal section 240A isheated to approximately 290° C. and fed to methanation unit 240B, wherethe remaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) are removed. Afterfurther cooling and drying of methanation product 243 at A4, theresulting gas stream 244 is combined with recycle gas 253 and compressedin synthesis loop compressor(s) C2/C3 to 3095 psia; the energy (e.g., toprovide work W2) for this compression is supplied by electricity. Thecombined and compressed gas stream 245 is preheated to approximately450° C. and sent to a series of three ammonia synthesis reactors 250A inseries with interstage cooling; per-pass conversion of nitrogen is 30%.The ammonia-containing product stream 251 is first cooled at A5,allowing for heat recovery for use in heating other process streams,then cooled again with air and cooling water, and finally cooled to −34°C. using refrigeration at A6 so that 125 t/hr liquid ammonia product 255may be recovered. The energy (e.g., W3) for refrigeration section at A6is supplied by renewable electricity. After ammonia recovery, a 17 t/hrpurge 205′ is taken from the remaining gases to allow for removal ofimpurities; the composition of this purge stream is approximately 12weight % CH₄, 11 weight % H₂, 75 weight % N₂, and 2% weight % NH₃. Theremainder of the gas stream 253 is then recycled back to synthesis loopcompressor(s) C2/C3.

There are four major energy consumers in the partially electrifiedprocess V of this Example 2: (1) regeneration of the amine solution inCO₂ removal 240A, (2) power (e.g., W1, W2, W3) to drive the three largecompressors, air compressor C1, synthesis loop compressor(s) C2/C3, andrefrigeration compressor at A6, (3) heating to raise the temperature(e.g., at feed pretreatment 110) of the feed gases and provide the heatof reaction for the primary reformer 220A, and (4) preheating of thefeed (e.g., at heating B2) before the first ammonia synthesis reactor250A. Smaller amounts of energy are used for a variety of otherpurposes. Some of the energy required for these operations can beobtained by heat exchange with streams that are being cooled (forexample, much of the heat required to preheat the methanation reactorfeed (e.g., at heating B1) can be obtained from heat removed whencooling the product gases from the same reactor (e.g., at A4)), but therest must be supplied externally. In Example 2, external energy issupplied in three places: the primary reformer 220A, the auxiliaryboiler 260, and power for the three large compressors (e.g., C1, C2/C3,and refrigeration compressor at A6). The primary reformer 220A is heatedelectrically; 72 MW of renewable electricity are used to generate 68 MWof heat. In contrast to Comparative Example 1, there is no convectionsection in the primary reformer furnace and no flue gas losses from thisheating. Auxiliary boiler 260 consumes 7.0 t/hr of natural gas with acontained chemical energy of 107 MW. An amount of 114 MW of electricityis supplied to three large compressors; at an efficiency of 93%, thisperforms the same work that required 424 MW of high pressure steam 263in Comparative Example 1. In addition, although some of the reactionsare endothermic (e.g., steam reforming at 220A), the net set ofreactions for Example 2 is exothermic and generates roughly 70 MW ofenergy that can be used elsewhere. How to most efficiently allocate thisenergy to the various consumers of energy in the process with thehighest efficiency is an engineering problem that can be addressed byone of skill in the art upon reading this disclosure via carefulmatching of temperatures, types of energy, and energy content. Energycan be transferred directly via heat exchange or it can be converted tosteam that can either be used for heat exchange or to do mechanicalwork, such as to drive a compressor. In Example 2 a strategy wasutilized that maximizes heat exchange between the various processstreams; assuming that available heat can be moved efficiently fromwhere it is available to where it is needed at a correspondingtemperature. This represents a maximal heat integration strategy andminimizes external energy inputs, but other arrangements are possible,as will be obvious to one skilled in the art. The use of combustion tosupply some of the external energy input needed for the process comeswith a concomitant disadvantage—the stack or flue gas from this boilercontains energy that cannot be usefully recovered because of its lowtemperature and difficulties in condensing water. In the process ofExample 2, this wasted energy amounts to only 22 MW, a reduction of 84%over Comparative Example 1. Energy is also lost in several process stepswhere streams are cooled but the heat cannot be usefully recovered, forexample in the final cooling of the product stream from ammoniasynthesis reactor at 250A.

Table 2 shows energy use values for the process of Example 2. As seen inTable 2, an amount of 107 MW of energy is supplied through thecombustion of natural gas in the auxiliary boiler 260, a reduction of84% over Comparative Example 1. An amount of 186 MW of renewableelectricity is supplied, and an additional 70 MW is obtained as the netexothermic heat of reaction. The total net energy input to the process Vis 363 MW, although a large amount (>400 MW) of energy is alsotransferred internally from the cooling of hot product streams to theheating of feed streams. Of the 72 MW supplied to the primary reformerat 220A, all is supplied to the reactor; there is no convection sectionin the primary reformer furnace and no flue gas in this embodiment. Anamount of 107 MW is supplied to the auxiliary boiler 260, of which 86 MWis used to supply heat for CO₂ removal 240A and 21 MW is lost to theatmosphere in the flue gas. In total, 22 MW, or 6.10% of the netexternal energy supplied, is lost in the flue gas from the auxiliaryboiler 260. An additional 12 MW, or 3.3% of the net external energysupplied, is lost due to inefficiencies in the use of electricity.

As further seen in the data in Table 2, total fuel gas consumption is56,000 tons per year. The combustion of this fuel results in theatmospheric emissions 0.155 million tons of CO₂ annually. An additional1.23 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 1.38 million tons per year, a decrease of39% over Comparative Example 1. Specific energy consumption includingthe fuel, electricity and heat of reaction is 10.5 GJ per ton of ammoniaproduced; specific energy consumption calculated only on the fuel andelectricity inputs is 8.4 GJ per ton of ammonia produced. An amount of9.4% of the total supplied energy is lost in the stack gas and due toelectrical inefficiencies; none is lost, in this embodiment, due toinefficiencies in the conversion of steam to mechanical work.

Example 3: Primary and Secondary Reforming with Electric Compressors andElectric Reboiler

Example 3 is a different partial electrification process VI as per anembodiment of this disclosure of the ammonia synthesis process describedin Comparative Example 1. In process VI, partial electrification isprovided by an electric reboiler (of CO₂ removal 240A) in addition tothe electric compressors of Example 1. The key elements of thiselectrified plant VI are shown in FIG. 8; except for the provision ofthe energy, the process is essentially the same as in ComparativeExample 1. An amount of 59 metric tons per hour (t/hr) of methane feed205 is fed to the process; the pretreatment of this methane feed toremove sulfur and other harmful components was not included in the modeland is not shown in FIG. 8. An amount of 194 t/hr water 211 is vaporizedand mixed with the methane feed. The resulting feed 215 is furtherpreheated and fed to primary reformer 220A at approximately 620° C. and690 psia, where CO, CO₂, and H₂ are produced. Energy Q1 is supplied toprimary reformer 220A by a natural gas fired furnace, which provides theheat of reaction and further heats the gases; the firing of this furnacealso results in energy input Q2, which is transferred in the convectionsection to preheat the feed water/methane mixture 215, and energy lossQ5, which is the energy lost in the flue gas. The product 221 fromprimary reformer 220A is combined with 149 t/hr preheated air feed 206and fed to secondary autothermal reformer 220B where further reactionoccurs, producing more CO, CO₂, and H₂. The energy for secondaryreformer 220B is supplied by the oxidation of methane, CO, and H₂ thatoccurs in the secondary reformer itself. The product 222 from secondaryreformer 220B is cooled (e.g., at cooling A1) to approximately 320° C.and passed through two water gas shift reactors 230, where additional H₂and CO₂ are formed. The product stream 234 from the water gas shiftreactors 230 is further cooled (e.g., at A3) and then purified in CO₂removal section 240A, where 154 t/hr CO₂ is removed by amine absorption.To release absorbed CO₂ and regenerate the amine solution, a significantamount of energy is required. Some of this energy is obtained by heatexchange with the cooling gas streams from the secondary reformer 220Band the water gas shift reactors 230, but additional energy Q3 must besupplied; in Example 3 this energy is obtained from electric heating(e.g., an electric reboiler). The purified product stream 241 from CO₂removal section 240A is heated to approximately 290° C. and fed tomethanation unit 240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1mol %) are removed. After further cooling and drying of the methanationproduct 243 at A4, the resulting gas stream 244 is combined with recyclegas 253 and compressed in synthesis loop compressor(s) C2/C3 to 3095psia; the energy for this compression (e.g., for work W2) is supplied byelectricity in this embodiment. The combined and compressed gas stream245 is preheated (e.g., at heating B2) to approximately 450° C. and sentto a series of three ammonia synthesis reactors 250A in series withinterstage cooling; per-pass conversion of nitrogen is 30%. Theammonia-containing product stream 251 is first cooled at A5, allowingfor heat recovery for use in heating other process streams, then cooledagain with air and cooling water, and finally cooled to −34° C. usingrefrigeration at A6 so that 125 t/hr liquid ammonia product 255 may berecovered. The energy for (e.g., work W3) refrigeration section at A6 issupplied by renewable electricity. After ammonia recovery, a 17 t/hrpurge 205′ is taken from the remaining gases to allow for removal ofimpurities; the composition of this purge stream is approximately 12weight % CH₄, 11 weight % H₂, 75 weight % N₂, and 2% weight % NH₃. Theremainder of the gas stream 253 is then recycled back to synthesis loopcompressor(s) C2/C3.

There are four major energy consumers in the partially electrifiedprocess VI of this Example 3: (1) regeneration of the amine solution inCO₂ removal 240A, (2) power (e.g., for work W1, W2, W3) to drive thethree large compressors, air compressor C1, synthesis loop compressor(s)C2/C3, and refrigeration compressor at A6, (3) heating to raise thetemperature of the feed gases (e.g., at feed pretreatment 110) andprovide the heat of reaction for the primary reformer 220A, and (4)preheating of the feed (e.g., at heating B2) before the first ammoniasynthesis reactor 250A. Smaller amounts of energy are used for a varietyof other purposes. Some of the energy required for these operations canbe obtained by heat exchange with streams that are being cooled (forexample, much of the heat required to preheat the methanation reactorfeed (e.g., at heating B1) can be obtained from heat removed whencooling (e.g., at A4) the product gases 243 from the same reactor), butthe rest must be supplied externally. In Example 3, external energy issupplied in three places: the primary reformer 220A, electric heatingfor regeneration of the amine stripping solution in the CO₂ removalsystem at 240A, and power for the three large compressors. The primaryreformer furnace of primary reformer 220A consumes 7.3 t/hr of naturalgas with a contained chemical energy (high-heating value, or HHV) of 111MW. An amount of 72 MW of electricity is supplied to the CO₂ removalsystem 240A, generating 68 MW of heat at an efficiency of 95%. An amountof 114 MW of electricity is supplied to three large compressors; at anefficiency of 93%, this performs the same work that required 424 MW ofhigh pressure steam 263 in Comparative Example 1. In addition, althoughsome of the reactions are endothermic (e.g., steam reforming at 220A),the net set of reactions for Example 3 is exothermic and generatesroughly 70 MW of energy that can be used elsewhere. How to mostefficiently allocate this energy to the various consumers of energy inthe process with the highest efficiency is an engineering problem thatcan be addressed by one of skill in the art upon reading this disclosurevia careful matching of temperatures, types of energy, and energycontent. Energy can be transferred directly via heat exchange or it canbe converted to steam that can either be used for heat exchange or to domechanical work, such as to drive a compressor. In Example 3 a strategyhas been utilized that maximizes heat exchange between the variousprocess streams; assuming that available heat can be moved efficientlyfrom where it is available to where it is needed at a correspondingtemperature. This represents a maximal heat integration strategy andminimizes external energy inputs, but other arrangements are possible,as will be obvious to one skilled in the art. The use of combustion tosupply some of the external energy input needed for the process comeswith a concomitant disadvantage—the stack or flue gas from this furnacecontains energy that cannot be usefully recovered because of its lowtemperature and difficulties in condensing water. In the process ofExample 3, this wasted energy amounts to only 23 MW, a reduction of 84%over Comparative Example 1. Energy is also lost in several process stepswhere streams are cooled but the heat cannot be usefully recovered, forexample in the final cooling of the product stream from ammoniasynthesis reactor at 250A.

Table 2 shows energy use values for the process of Example 3. As seen inTable 2, an amount of 111 MW of energy is supplied through thecombustion of natural gas in the secondary reformer furnace at 220A, butno energy is supplied through an auxiliary boiler. An amount of 186 MWof renewable electricity is supplied. An additional 70 MW is obtained asthe net exothermic heat of reaction. The total net energy input to theprocess is 367 MW, although a large amount (>400 MW) of energy is alsotransferred internally from the cooling of hot product streams to theheating of feed streams. In total, 23 MW, or 6.3% of the net externalenergy supplied, is lost in the flue gas (e.g., from the reformerfurnace at 220A). An additional 12 MW, or 3.3% of the net externalenergy supplied, is lost due to inefficiencies in the use ofelectricity.

As further seen in the data in Table 2, total fuel gas consumption is58,000 tons per year. The combustion of this fuel results in theatmospheric emissions 0.160 million tons of CO₂ annually. An additional1.23 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 1.39 million tons per year, a decrease of39% over Comparative Example 1. Specific energy consumption includingthe fuel, electricity, and heat of reaction is 10.6 GJ per ton ofammonia produced; specific energy consumption calculated only on thefuel and electricity inputs is 8.6 GJ per ton of ammonia produced. 9.5%of the total supplied energy is lost in the stack gas and due toelectrical inefficiencies; none is lost, in this embodiment, due toinefficiencies in the conversion of steam to mechanical work.

Example 4: Primary and Secondary Reforming—all Electric

Example 4 is a near-complete electrification process VII as per anembodiment of this disclosure of the ammonia synthesis process describedin Comparative Example 1; no external energy is supplied fromcombustion, although there is still some combustion inside the processdue to the oxidation of methane, carbon monoxide, and hydrogen in thesecondary autothermal reformer at 220B. In process VII, near-completeelectrification is provided by electric compressors (as in Examples1-3), an electric furnace in primary reformer 220A (as in Example 2),and an electric reboiler (as in Example 3). The key elements of thiselectrified plant or process VII are shown in FIG. 9; except for theprovision of the energy, the process is essentially the same as inComparative Example 1. An amount of 59 metric tons per hour (t/hr) ofmethane feed 205 is fed to the process; the pretreatment of this methanefeed to remove sulfur and other harmful components was not included inthe model and is not shown in FIG. 8. An amount of 194 t/hr water 211 isvaporized and mixed with the methane feed. The resulting feed 215 isfurther preheated (e.g., at feed pretreatment 110) and fed to primaryreformer 220A at approximately 620° C. and 690 psia, where CO, CO₂, andH₂ are produced. Energy Q1 is supplied to primary reformer 220A byelectric heating, which provides the heat of reaction and further heatsthe gases. The product from primary reformer 221 is combined with 149t/hr preheated air feed 206 and fed to secondary autothermal reformer220B where further reaction occurs, producing more CO, CO₂, and H₂. Theenergy for secondary reformer 220B is supplied by the oxidation ofmethane, CO, and H₂ that occurs in the secondary reformer 220B. Theproduct 222 from secondary reformer 220B is cooled (e.g., at cooling A1)to approximately 320° C. and passed through two water gas shift reactors230, where additional H₂ and CO₂ are formed. The product stream 234 fromthe water gas shift reactors 230 is further cooled (e.g., at coolingA1/A2) and then purified in CO₂ removal section 240A, where 154 t/hr CO₂is removed by amine absorption. To release absorbed CO₂ and regeneratethe amine solution, a significant amount of energy is required. Some ofthis energy is obtained by heat exchange with the cooling gas streamsfrom the secondary reformer 220B and the water gas shift reactors 230,but additional energy Q3 must be supplied; in Example 4 this energy isobtained from electric heating. The purified product stream 241 from CO₂removal section 240A is heated to approximately 290° C. and fed tomethanation unit 240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1mol %) are removed. After further cooling and drying of the methanationproduct 243 at A4, the resulting gas stream 244 is combined with recyclegas 253 and compressed in synthesis loop compressor(s) C2/C3 to 3095psia; the energy for this compression is supplied by electricity, inthis embodiment. The combined and compressed gas stream 245 is preheated(e.g., at heating B2) to approximately 450° C. and sent to a series ofthree ammonia synthesis reactors 250A in series with interstage cooling;per-pass conversion of nitrogen is 30%. The ammonia-containing productstream 251 is first cooled at A5, allowing for heat recovery for use inheating other process streams, then cooled again with air and coolingwater, and finally cooled to −34° C. using refrigeration at A6 so that125 t/hr liquid ammonia product 255 may be recovered. The energy forrefrigeration section A6 is supplied by renewable electricity, in thisembodiment. After ammonia recovery, a 17 t/hr purge 205′ is taken fromthe remaining gases to allow for removal of impurities; the compositionof this purge stream is approximately 12 weight % CH₄, 11 weight % H₂,75 weight % N₂, and 2% weight % NH₃. The remainder of the gas stream 253is then recycled back to synthesis loop compressor(s) C2/C3.

There are four major energy consumers in the electrified process of thisExample 4: (1) regeneration of the amine solution in CO₂ removal 240A,(2) power (e.g., W1, W2, W3) to drive the three large compressors, aircompressor C1, synthesis loop compressor(s) C2/C3, and refrigerationcompressor at A6, (3) heating (e.g., at feed pretreatment 110) to raisethe temperature of the feed gases and provide the heat of reaction forthe primary reformer 220A, and (4) preheating (e.g., at heating B2) ofthe feed before the first ammonia synthesis reactor at 250A. Smalleramounts of energy are used for a variety of other purposes. Some of theenergy required for these operations can be obtained by heat exchangewith streams that are being cooled (for example, much of the heatrequired to preheat (e.g., at heating B1) the methanation reactor feedcan be obtained from heat removed when cooling (e.g., at A4) the productgases from the same reactor), but the rest must be supplied externally.In Example 4, external energy is supplied in three places: the primaryreformer at 220A, heating for regeneration of the amine strippingsolution in the CO₂ removal system at 240A, and power for the threelarge compressors. All of this energy is supplied electrically inExample 4. The primary reformer at 220A is heated electrically; 72 MW ofrenewable electricity are used to generate 68 MW of heat. In contrast toComparative Example 1, there is no convection section in the primaryreformer furnace and no flue gas losses from this heating. An amount of72 MW of electricity is supplied to the CO₂ removal system 240A,generating 68 MW of heat at an efficiency of 95%. An amount of 114 MW ofelectricity is supplied to the three large compressors; at an efficiencyof 93%, this performs the same work that required 424 MW of highpressure steam 263 in Comparative Example 1. In addition, although someof the reactions are endothermic (e.g., steam reforming at 220A), thenet set of reactions for Example 4 is exothermic and generates roughly70 MW of energy that can be used elsewhere. How to most efficientlyallocate this energy to the various consumers of energy in the processwith the highest efficiency is an engineering problem that can beaddressed by one of skill in the art upon reading this disclosure viacareful matching of temperatures, types of energy, and energy content.Energy can be transferred directly via heat exchange or it can beconverted to steam that can either be used for heat exchange or to domechanical work, such as to drive a compressor. In Example 4 a strategyhas been utilized that maximizes heat exchange between the variousprocess streams; assuming that available heat can be moved efficientlyfrom where it is available to where it is needed at a correspondingtemperature. This represents a maximal heat integration strategy andminimizes external energy inputs, but other arrangements are possible,as will be obvious to one skilled in the art. The use of combustion tosupply some of the external energy input needed for the process comeswith a concomitant disadvantage—the stack or flue gas from furnaces andboilers contains energy that cannot be usefully recovered because of itslow temperature and difficulties in condensing water. In the process ofExample 4, there are no flue gas losses, a reduction of 100% overComparative Example 1. Energy is also lost in several process stepswhere streams are cooled but the heat cannot be usefully recovered, forexample in the final cooling of the product stream from ammoniasynthesis reactor 250A

Table 2 shows energy use values for the process VII of Example 4. Asseen in Table 2, 276 MW of renewable electricity are supplied. Anadditional 70 MW is obtained as the net exothermic heat of reaction. Thetotal net energy input to the process is 347 MW, although a large amount(>400 MW) of energy is also transferred internally from the cooling ofhot product streams to the heating of feed streams. Only 16 MW, or 4.6%of the net external energy supplied, is lost due to inefficiencies inthe use of electricity.

As further seen in the data in Table 2, no fuel gas is consumed inExample 4. Because of this, the only CO₂ emitted is the 1.23 milliontons of CO₂ formed by the process chemistry itself; this represents adecrease of 46% over Comparative Example 1. Specific energy consumptionincluding the electricity and the heat of reaction is 10.0 GJ per ton ofammonia produced; specific energy consumption calculated only on theelectrical inputs is 8.0 GJ per ton of ammonia produced. The amount ofenergy lost due to inefficiencies in energy use, 16 MW, is only aboutone-thirtieth of the energy lost to flue gas and steam-to-mechanicalenergy conversion in Comparative Example 1.

Comparative Example 2: Conventional Ammonia Synthesis Via Primary (SMR)Reforming Only

A process simulation was performed to determine the heat and mass flowsfor a process VIII for the production of ammonia. The process simulationutilized in this Comparative Example 2 was made using Aspen Plus®. Theprocess of Comparative Example 2, shown in FIG. 10, illustrates analternative design for the synthesis of ammonia, one in which anautothermal reformer is not used, in contrast to Comparative Example 1and Examples 1-4 above, where an autothermal reformer generates heatinternally by the combustion of process methane, CO, and hydrogen. Thedesign parameters were taken from knowledge of specific plants, as wellas literature information on typical process operations. Althoughvariations will be obvious to one skilled in the art, this ComparativeExample 2 represents a process that can be used as a basis for comparingthe effects of electrification modifications according to embodiments ofthis disclosure. Although the processes of FIGS. 10-14 comprise a solereforming section, this reforming section will be referred tohereinafter as a primary reforming section.

The process VIII of Comparative Example 2 is configured to produce 125metric tons per hour of ammonia. If operated for a typical 8000 hours ina year, this would result in the production of one million tons ofammonia, although variations in downtime due to upsets and maintenancecould increase or reduce this output. This size is typical of largeammonia plants being built today.

As shown in FIG. 10 (which has been simplified to show only theessential features of the process of this Comparative Example 2), 53metric tons per hour (t/hr) of pure methane feed 205 are fed to theprocess; the pretreatment of this methane feed to remove sulfur andother harmful components was not included in the model and is not shownin FIG. 10. An amount of 176 t/hr water 211 is vaporized and mixed withthe methane feed. The resulting feed 215 is further preheated (e.g., atfeed pretreatment 110) and fed to primary reformer 220A (which may be asole reformer or reformer section) at approximately 690 psia, where CO,CO₂, and H₂ are produced. Energy Q1 is supplied to primary reformer 220Aby a natural gas fired furnace, which supplies the heat of reaction andfurther heats the gases. The product 221 from primary reformer 220A iscooled (e.g., at cooling A1) to approximately 320° C. and passed throughtwo water gas shift reactors 230, where additional H₂ and CO₂ areformed. The product stream 234 from the water gas shift reactors 230 isfurther cooled (e.g., at cooling A2 and/or A3) and then purified in CO₂removal section 240A, where 129 t/hr CO₂ is removed by amine absorption.To release absorbed CO₂ and regenerate the amine solution, a significantamount of energy is required. Some of this energy is obtained by heatexchange with the cooling gas streams from the primary reformer 220A andthe water gas shift reactors 230, but additional energy Q3 must besupplied; this energy is obtained from auxiliary boiler 260 via theproduction and use of medium pressure steam 262 from BFW 261. Thepurified product stream 241 from CO₂ removal section 240A is heated(e.g., at heating B1) to approximately 290° C. and fed to methanationunit 240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) areremoved. After further cooling and drying of the methanation product 243at A4, an amount of 109 t/hr of nitrogen 266 is added, and the resultinggas stream 244 is combined with recycle gas 253 and compressed insynthesis loop compressor(s) C2 and/or C3 to 3095 psia; the energy forthis compression (e.g., work W2) is supplied by high pressure steamobtained from auxiliary boiler 260. The combined and compressed gasstream 245 is preheated to approximately 450° C. (e.g., at heating B2)and sent to a series of three ammonia synthesis reactors 250A in serieswith interstage cooling; per-pass conversion of nitrogen is 33%. Theammonia-containing product stream 251 is first cooled at A5, allowingfor heat recovery for use in heating other process streams, then cooledagain with air and cooling water, and finally cooled to −34° C. usingrefrigeration at A6 so that 125 t/hr liquid ammonia product 255 may berecovered. The energy for refrigeration section A6 (e.g., work W3) issupplied by high pressure steam 263 obtained from auxiliary boiler 260.After ammonia recovery, a 17 t/hr purge 205′ is taken from the remaininggases to allow for removal of impurities; the composition of this purgestream is approximately 25 weight % CH₄, 11 weight % H₂, 62 weight % N₂,and 2% weight % NH₃. The remainder of the gas stream 253 is thenrecycled back to synthesis loop compressor(s) C2 and/or C3.

There are four major energy consumers in the conventional process VIIIof this Comparative Example 2: (1) regeneration of the amine solution inCO₂ removal 240A, (2) power to drive the two large compressors viacompressor turbines 265: synthesis loop compressor(s) C2/C3 andrefrigeration compressor at A6, (3) heating (e.g., at feed pretreatment110) to raise the temperature of the feed gases and provide the heat ofreaction for the primary reformer 220A, and (4) preheating (e.g., atheating B2) of the feed before the first ammonia synthesis reactor 250A.As is common, very little electricity is consumed, primarily for somesmaller pumps. Some of the energy required for these operations can beobtained by heat exchange with streams that are being cooled (forexample, much of the heat required to preheat (e.g., at heating B1) themethanation reactor feed can be obtained from heat removed when cooling(e.g., at A4) the product gases from the same reactor), but the restmust be supplied externally and is conventionally generated by burningfuel. In Comparative Example 2, external energy is supplied in twoplaces: the primary reformer furnace of primary reformer 220A, and theauxiliary boiler 260. The primary reformer furnace consumes 21.1 t/hr ofnatural gas with a contained chemical energy (high-heating value, orHHV) of 322 MW. Auxiliary boiler 260 consumes 29.9 t/hr of natural gaswith a contained chemical energy of 455 MW. In addition, although someof the reactions are exothermic (e.g., ammonia synthesis at 250A), thenet set of reactions for Comparative Example 2 is endothermic andrequires roughly 67 MW of energy to be provided. (In contrast, the netset of reactions for Comparative Example 1 was exothermic.) How to mostefficiently allocate the available energy to the various consumers ofenergy in the process with the highest efficiency is an engineeringproblem that can be addressed by one of skill in the art upon readingthis disclosure via careful matching of temperatures, types of energy,and energy content. Energy can be transferred directly via heat exchangeor it can be converted to steam that can either be used for heatexchange or to do mechanical work, such as to drive a compressor. InComparative Example 2 a strategy has been utilized that maximizes heatexchange between the various process streams; assuming that availableheat can be moved efficiently from where it is available to where it isneeded at a corresponding temperature. This represents a maximal heatintegration strategy and minimizes external energy inputs, but otherarrangements are possible, as will be obvious to one skilled in the art.The use of combustion to supply some of the external energy input neededfor the process comes with a concomitant disadvantage—the stack or fluegas from these furnaces and boilers contains energy that cannot beusefully recovered because of its low temperature and difficulties incondensing water. For example, in the process of Comparative Example 2,this wasted energy amounts to 155 MW. Energy is also lost in severalprocess steps where streams are cooled but the heat cannot be usefullyrecovered, for example in the final cooling of the product stream fromammonia synthesis reactor 250A.

Table 3 shows energy use values for the process VIII of ComparativeExample 2. As seen in Table 3, an amount of 777 MW of energy is suppliedthrough the combustion of natural gas in the reformer furnace of primaryreformer 220A and the auxiliary boiler 260. Of this energy, 67 MW isrequired to supply the net endothermic heat of reaction. Aftersubtracting this, the available net energy input to the process forother uses is 710 MW, although a large amount (>400 MW) of energy isalso transferred internally from the cooling of hot product streams tothe heating of feed streams. Of the 322 MW consumed in the primaryreformer furnace, the radiant section is used to provide 168 MW tofurther heat the gases and supply the heat of reaction; an additional 90MW is transferred in the convection section to provide process heat. Theremaining 64 MW is lost to the atmosphere in the flue gas. An amount of455 MW is supplied to the auxiliary boiler 260, of which 15 MW is usedto supply heat for CO₂ removal 240A and 349 MW provides the power forthe two large compressors, synthesis loop compressor(s) C2/C3, and therefrigeration compressor at A6; 91 MW is lost to the atmosphere in theflue gas. In total, 155 MW, or 22% of the net available energy supplied,is lost in the flue gas from the reformer furnace at primary reformer220A and auxiliary boiler 260.

As further seen in the data in Table 3, the total fuel gas consumptionis 448,000 tons per year. The combustion of this fuel results in theatmospheric emissions 1.23 million tons of CO₂ annually. An additional1.1 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 2.33 million tons per year. Specificenergy consumption after subtracting the heat of reaction from the fuelinputs is 19.2 GJ per ton of ammonia produced; specific energyconsumption calculated only on the fuel inputs is 21.0 GJ per ton ofammonia produced. An amount of 37% of the net available energy (262 MWout of 710 MW) is lost due to inefficiencies in the conversion of steamto mechanical work; another 22% (155 MW) of the total supplied energy islost to the atmosphere from the stack gas.

Example 5: Primary (SMR) Reforming Only with Electric Compressors

Example 5 is a partial electrification process IX as per an embodimentof this disclosure of the ammonia synthesis process described inComparative Example 2. In process IX, partial electrification isprovided by electric compressors. The key elements of this electrifiedplant IX are shown in FIG. 11; except for the provision of the energy,the process is essentially the same as in Comparative Example 2. Theprocess of Example 5 is configured to produce 125 metric tons per hourof ammonia. If operated for a typical 8000 hours in a year, this wouldresult in the production of one million tons of ammonia, althoughvariations in downtime due to upsets and maintenance could increase orreduce this output. This size is typical of large ammonia plants beingbuilt today.

As shown in FIG. 11 (which has been simplified to show only theessential features of the process of this Example 5), 53 metric tons perhour (t/hr) of methane feed 205 are fed to the process; the pretreatmentof this methane feed to remove sulfur and other harmful components wasnot included in the model and is not shown in FIG. 11. An amount of 176t/hr water 211 is vaporized and mixed with the methane feed. Theresulting feed 215 is further preheated (e.g., at feed pretreatment 110)and fed to primary reformer 220A at approximately 690 psia, where CO,CO₂, and H₂ are produced. Energy Q1 is supplied to primary reformer 220Aby a natural gas fired furnace, which supplies the heat of reaction andfurther heats the gases. The product 221 from primary reformer 220A iscooled (e.g., at cooling A1) to approximately 320° C. and passed throughtwo water gas shift reactors 230, where additional H₂ and CO₂ areformed. The product stream 234 from the water gas shift reactors 230 isfurther cooled (e.g., at cooling A2 and/or A3) and then purified in CO₂removal section 240A, where 129 t/hr CO₂ is removed by amine absorption.To release absorbed CO₂ and regenerate the amine solution, a significantamount of energy is required. Some of this energy is obtained by heatexchange with the cooling gas streams from the primary reformer 220A andthe water gas shift reactors 230, but additional energy Q3 must besupplied; this energy is obtained from auxiliary boiler 260 via theproduction and use of medium pressure steam 262 from BFW 261. Thepurified product stream 241 from CO₂ removal section 240A is heated(e.g., at heating B1) to approximately 290° C. and fed to methanationunit 240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) areremoved. After further cooling and drying of methanation product 243 atA4, 109 t/hr of nitrogen 266 is added, and the resulting gas stream 244is combined with recycle gas 253 and compressed in synthesis loopcompressor(s) C2/C3 to 3095 psia; the energy for this compression (e.g.,for work W2) is supplied by renewable electricity in this embodiment.The combined and compressed gas stream 245 is preheated (e.g., atheating B2) to approximately 450° C. and sent to a series of threeammonia synthesis reactors 250A in series with interstage cooling;per-pass conversion of nitrogen is 33%. The ammonia-containing productstream 251 is first cooled at A5, allowing for heat recovery for use inheating other process streams, then cooled again with air and coolingwater, and finally cooled to −34° C. using refrigeration at secondcooling A6 so that 125 t/hr liquid ammonia product 255 may be recovered.The energy for refrigeration section A6 (e.g., for work W3) is suppliedby renewable electricity in this embodiment. After ammonia recovery, a17 t/hr purge 205′ is taken from the remaining gases to allow forremoval of impurities; the composition of this purge stream isapproximately 25 weight % CH₄, 11 weight % H₂, 62 weight % N₂, and 2%weight % NH₃. The remainder of the gas stream 253 is then recycled backto synthesis loop compressor(s) C2/C3.

There are four major energy consumers in the conventional process IX ofthis Example 5: (1) regeneration of the amine solution in CO₂ removal at240A, (2) power to drive the two large compressors, synthesis loopcompressor(s) C2/C3 and refrigeration compressor at A6, (3) heating(e.g., at feed pretreatment 110) to raise the temperature of the feedgases and provide the heat of reaction for the primary reformer 220A,and (4) preheating of the feed (e.g., at heating B2) before the firstammonia synthesis reactor 250A. Smaller amounts of energy are used for avariety of other purposes. Some of the energy required for theseoperations can be obtained by heat exchange with streams that are beingcooled (for example, much of the heat required to preheat (e.g., atheating B1) the methanation reactor feed can be obtained from heatremoved (e.g., at A4) when cooling the product gases 243 from the samereactor), but the rest must be supplied externally. In Example 5,external energy is supplied in three places: the primary reformerfurnace at primary reformer 220A, the auxiliary boiler 260, andrenewable electricity used to power the large compressors. The primaryreformer furnace consumes 21.1 t/hr of natural gas with a containedchemical energy (high-heating value, or HHV) of 322 MW. Auxiliary boiler260 consumes 1.2 t/hr of natural gas with a contained chemical energy of18 MW. An amount of 94 MW of electricity is supplied to the two largecompressors; at an efficiency of 93%, this performs the same work thatrequired 349 MW of high pressure steam 263 in Comparative Example 2. Inaddition, although some of the reactions are exothermic (e.g., ammoniasynthesis at 250A), the net set of reactions for Example 5 isendothermic and requires roughly 67 MW of energy to be provided. How tomost efficiently allocate the available energy to the various consumersof energy in the process with the highest efficiency is an engineeringproblem that can be addressed by one of skill in the art upon readingthis disclosure via careful matching of temperatures, types of energy,and energy content. Energy can be transferred directly via heat exchangeor it can be converted to steam that can either be used for heatexchange or to do mechanical work, such as to drive a compressor. InExample 5 a strategy has been utilized that maximizes heat exchangebetween the various process streams; assuming that available heat can bemoved efficiently from where it is available to where it is needed at acorresponding temperature. This represents a maximal heat integrationstrategy and minimizes external energy inputs, but other arrangementsare possible, as will be obvious to one skilled in the art. The use ofcombustion to supply some of the external energy input needed for theprocess comes with a concomitant disadvantage—the stack or flue gas fromthese furnaces and boilers contains energy that cannot be usefullyrecovered because of its low temperature and difficulties in condensingwater. For example, in the process of Example 5, this wasted energyamounts to 68 MW, a reduction of 56% over Comparative Example 2. Energyis also lost in several process steps where streams are cooled but theheat cannot be usefully recovered, for example in the final cooling ofthe product stream from ammonia synthesis reactor at 250A.

Table 3 shows energy use values for the process IX of Example 5. As seenin Table 3, an amount of 340 MW of energy is supplied through thecombustion of natural gas in the reformer furnace of primary reformer220A and the auxiliary boiler 260, a reduction of 56% over ComparativeExample 2. An additional 94 MW of energy is supplied as electricity. Ofthe total energy, 67 MW is required to supply the net endothermic heatof reaction. After subtracting this, the available net energy input tothe process for other uses is 367 MW, although a large amount (>400 MW)of energy is also transferred internally from the cooling of hot productstreams to the heating of feed streams. Of the 322 MW consumed in theprimary reformer furnace, the radiant section is used to provide 168 MWto further heat the gases and supply the heat of reaction; an additional90 MW is transferred in the convection section to provide process heat.The remaining 64 MW is lost to the atmosphere in the flue gas. An amountof 18 MW is supplied to the auxiliary boiler 260, of which 15 MW is usedto supply heat for CO₂ removal 240A; 91 MW is lost to the atmosphere inthe flue gas. In total, 68 MW, or 19% of the net available energysupplied, is lost in the flue gas from the reformer furnace of primaryreformer 220A and auxiliary boiler 260.

As further seen in the data in Table 3, the total fuel gas consumptionof process IX is 179,000 tons per year. The combustion of this fuelresults in the atmospheric emissions 0.49 million tons of CO₂ annually.An additional 1.1 million tons of CO₂ are emitted from the processchemistry itself, giving total CO₂ emissions of 1.59 million tons peryear, a decrease of 32% over Comparative Example 2. Specific energyconsumption after subtracting the heat of reaction from the fuel andelectricity inputs is 9.9 GJ per ton of ammonia produced; specificenergy consumption calculated only on the fuel and electricity inputs is11.8 GJ per ton of ammonia produced. An amount of 19% of the totalavailable energy is lost to the atmosphere from the stack gas, but noneis lost due to inefficiencies in the conversion of steam to mechanicalwork, in contrast to Comparative Example 2 where 22% and 37%,respectively, of the energy was lost in these ways.

Example 6: Primary (SMR) Reforming Only with Electric Compressors andElectric Reformer

Example 6 is a partial electrification process X as per an embodiment ofthis disclosure of the ammonia synthesis process described inComparative Example 2. In process X, partial electrification is providedby an electric furnace of primary reformer 220A in addition to theelectric compressors of Example 5. The key elements of this electrifiedplant X are shown in FIG. 12; except for the provision of the energy,the process is essentially the same as in Comparative Example 2. Theprocess of Example 6 is configured to produce 125 metric tons per hourof ammonia. If operated for a typical 8000 hours in a year, this wouldresult in the production of one million tons of ammonia, althoughvariations in downtime due to upsets and maintenance could increase orreduce this output. This size is typical of large ammonia plants beingbuilt today.

As shown in FIG. 12 (which has been simplified to show only theessential features of the process of this Example 6), 53 metric tons perhour (t/hr) of methane feed 205 are fed to the process; the pretreatmentof this methane feed to remove sulfur and other harmful components wasnot included in the model and is not shown in FIG. 12. An amount of 176t/hr water 211 is vaporized and mixed with the methane feed. Theresulting feed 215 is further preheated (e.g., at feed pretreatment 110)and fed to primary reformer 220A at approximately 690 psia, where CO,CO₂, and H₂ are produced. Energy Q1 is supplied to primary reformer 220Aby electric heating, which supplies the heat of reaction and furtherheats the gases. The product 221 from primary reformer 220A is cooled(e.g., at cooling A1) to approximately 320° C. and passed through twowater gas shift reactors 230, where additional H₂ and CO₂ are formed.The product stream 234 from the water gas shift reactors 230 is furthercooled (e.g., at cooling A2 and/or A3) and then purified in CO₂ removalsection 240A, where 129 t/hr CO₂ is removed by amine absorption. Torelease absorbed CO₂ and regenerate the amine solution, a significantamount of energy is required. Some of this energy is obtained by heatexchange with the cooling gas streams from the primary reformer 220A andthe water gas shift reactors 230, but additional energy Q3 must besupplied; this energy is obtained from auxiliary boiler 260 via theproduction and use of medium pressure steam 262 from BFW 261. Thepurified product stream 241 from CO₂ removal section 240A is heated(e.g., at heating B1) to approximately 290° C. and fed to methanationunit 240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) areremoved. After further cooling and drying of methanation product 243 atA4, 109 t/hr of nitrogen 266 is added, and the resulting gas stream 244is combined with recycle gas 253 and compressed in synthesis loopcompressor(s) C2/C3 to 3095 psia; the energy for this compression (e.g.,for work W2) is supplied by electricity in this embodiment. The combinedand compressed gas stream 245 is preheated (e.g., in heating B2) toapproximately 450° C. and sent to a series of three ammonia synthesisreactors 250A in series with interstage cooling; per-pass conversion ofnitrogen is 33%. The ammonia-containing product stream 251 is firstcooled at A5, allowing for heat recovery for use in heating otherprocess streams, then cooled again with air and cooling water, andfinally cooled to −34° C. using refrigeration at A6 so that 125 t/hrliquid ammonia product 255 may be recovered. The energy forrefrigeration section at A6 (e.g., for work W3) is supplied by renewableelectricity in this embodiment. After ammonia recovery, a 17 t/hr purge205′ is taken from the remaining gases to allow for removal ofimpurities; the composition of this purge stream is approximately 25weight % CH₄, 11 weight % H₂, 62 weight % N₂, and 2% weight % NH₃. Theremainder of the gas stream 253 is then recycled back to synthesis loopcompressor(s) C2/C3.

There are four major energy consumers in the process X of this Example6: (1) regeneration of the amine solution in CO₂ removal 240A, (2) powerto drive the two large compressors, e.g., work W2 and W3 required forsynthesis loop compressor(s) C2/C3 and refrigeration compressor at A6,respectively, (3) heating (e.g., at feed pretreatment 110) to raise thetemperature of the feed gases and provide the heat of reaction for theprimary reformer 220A, and (4) preheating (e.g., at heating B2) of thefeed before the first ammonia synthesis reactor 250A. Smaller amounts ofenergy are used for a variety of other purposes. Some of the energyrequired for these operations can be obtained by heat exchange withstreams that are being cooled (for example, much of the heat required topreheat (e.g., at heating B1) the methanation reactor feed can beobtained from heat removed when cooling (e.g., at A4) the product gasesfrom the same reactor), but the rest must be supplied externally. InExample 6, external energy is supplied in three places: the primaryreformer furnace of primary reformer 220A, the auxiliary boiler 260, andrenewable electricity used to power the two large compressors. Theprimary reformer 220A is heated electrically in this embodiment; 210 MWof renewable electricity are used to generate 200 MW of heat. Incontrast to Comparative Example 2, there is no convection section in theprimary reformer furnace and no flue gas losses from this heating.Auxiliary boiler 260 consumes 5.5 t/hr of natural gas with a containedchemical energy of 84 MW. An amount of 94 MW of electricity is suppliedto the two large compressors; at an efficiency of 93%, this performs thesame work that required 349 MW of high pressure steam 263 in ComparativeExample 2. In addition, although some of the reactions are exothermic(e.g., ammonia synthesis at 250A), the net set of reactions for Example6 is endothermic and requires roughly 67 MW of energy to be provided.How to most efficiently allocate the available energy to the variousconsumers of energy in the process with the highest efficiency is anengineering problem that can be addressed by one of skill in the artupon reading this disclosure via careful matching of temperatures, typesof energy, and energy content. Energy can be transferred directly viaheat exchange or it can be converted to steam that can either be usedfor heat exchange or to do mechanical work, such as to drive acompressor. In Example 6 a strategy has been utilized that maximizesheat exchange between the various process streams; assuming thatavailable heat can be moved efficiently from where it is available towhere it is needed at a corresponding temperature. This represents amaximal heat integration strategy and minimizes external energy inputs,but other arrangements are possible, as will be obvious to one skilledin the art. The use of combustion to supply some of the external energyinput needed for the process comes with a concomitant disadvantage—thestack or flue gas from these furnaces and boilers contains energy thatcannot be usefully recovered because of its low temperature anddifficulties in condensing water. For example, in the process of Example6, this wasted energy amounts to 17 MW, a reduction of 89% overComparative Example 2. Energy is also lost in several process stepswhere streams are cooled but the heat cannot be usefully recovered, forexample in the final cooling of the product stream from ammoniasynthesis reactor at 250A.

Table 3 shows energy use values for the process of Example 6. As seen inTable 3, an amount of 84 MW of energy is supplied through the combustionof natural gas in the auxiliary boiler 260, a reduction of 89% over fuelconsumption in Comparative Example 2. An additional 304 MW of energy issupplied as electricity. Of the total energy, 67 MW is required tosupply the net endothermic heat of reaction. After subtracting this, theavailable net energy input to the process for other uses is 321 MW,although a large amount (>400 MW) of energy is also transferredinternally from the cooling of hot product streams to the heating offeed streams. Of the 72 MW of renewable electricity supplied to theprimary reformer 220A, all is supplied to the reactor; there is noconvection section and no flue gas produced in primary reformer 220A ofthis embodiment. An amount of 84 MW is supplied to the auxiliary boiler260, of which 67 MW is used to supply heat for CO₂ removal 240A; 17 MW,or 5.3% of the net external energy available, is lost to the atmospherein the flue gas. An additional 17 MW, or 5.3% of the net external energyavailable, is lost due to inefficiencies in the use of electricity.

As further seen in the data in Table 3, the total fuel gas consumptionis 44,000 tons per year. The combustion of this fuel results in theatmospheric emissions 0.12 million tons of CO₂ annually. An additional1.1 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 1.22 million tons per year, a decrease of48% over Comparative Example 2. Specific energy consumption aftersubtracting for the heat of reaction from the fuel and electricityinputs is 8.7 GJ per ton of ammonia produced; specific energyconsumption calculated only on the fuel and electricity inputs is 10.5GJ per ton of ammonia produced. Only 5% of the total available energy islost to the atmosphere from the stack gas, but none is lost due toinefficiencies in the conversion of steam to mechanical work, incontrast to Comparative Example 2 where 22% and 37%, respectively, ofthe energy was lost in these ways.

Example 7: Primary (SMR) Reforming Only with Electric Compressors andElectric Reboiler

Example 7 is a partial electrification process XI as per an embodimentof this disclosure of the ammonia synthesis process described inComparative Example 2. In process XI, partial electrification isprovided by an electric reboiler (as in Example 3) in addition to theelectric compressors of Example 5. The key elements of this electrifiedplant XI are shown in FIG. 13; except for the provision of the energy,the process is essentially the same as in Comparative Example 2. Theprocess of Example 7 is configured to produce 125 metric tons per hourof ammonia. If operated for a typical 8000 hours in a year, this wouldresult in the production of one million tons of ammonia, althoughvariations in downtime due to upsets and maintenance could increase orreduce this output. This size is typical of large ammonia plants beingbuilt today.

As shown in FIG. 13 (which has been simplified to show only theessential features of the process of this Example 7), 53 metric tons perhour (t/hr) of methane feed 205 are fed to the process; the pretreatmentof this methane feed to remove sulfur and other harmful components wasnot included in the model and is not shown in FIG. 13. An amount of 176t/hr water 211 is vaporized and mixed with the methane feed. Theresulting feed 215 is further preheated (e.g., at feed pretreatment 110)and fed to primary reformer 220A at approximately 690 psia, where CO,CO₂, and H₂ are produced. Energy Q1 is supplied to primary reformer 220Aby a natural gas fired furnace, which supplies the heat of reaction andfurther heats the gases. The product 221 from primary reformer 220A iscooled (e.g., at cooling A1) to approximately 320° C. and passed throughtwo water gas shift reactors 230, where additional H₂ and CO₂ areformed. The product stream from the water gas shift reactors 230 isfurther cooled (e.g., at cooling A2/A3; as utilized herein, A2/A3 means‘A2 and/or A3’) and then purified in CO₂ removal section 240A, where 129t/hr CO₂ is removed by amine absorption. To release absorbed CO₂ andregenerate the amine solution, a significant amount of energy isrequired. Some of this energy is obtained by heat exchange with thecooling gas streams from the primary reformer 220A and the water gasshift reactors 230, but additional energy Q3 must be supplied; inExample 7, this energy is obtained heating with renewable electricity.The purified product stream 241 from CO₂ removal section 240A is heatedto approximately 290° C. and fed to methanation unit 240B, where theremaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) are removed. Afterfurther cooling and drying of methanation product 243 at A4, 109 t/hr ofnitrogen 266 is added, and the resulting gas stream 244 is combined withrecycle gas 253 and compressed in synthesis loop compressor(s) C2/C3 to3095 psia; the energy for this compression (e.g., to provide work W2) issupplied by renewable electricity in this embodiment. The combined andcompressed gas stream 245 is preheated (e.g., at heating B2) toapproximately 450° C. and sent to a series of three ammonia synthesisreactors 250A in series with interstage cooling; per-pass conversion ofnitrogen is 33%. The ammonia-containing product stream 251 is firstcooled at A5, allowing for heat recovery for use in heating otherprocess streams, then cooled again with air and cooling water, andfinally cooled to −34° C. using refrigeration at A6 so that 125 t/hrliquid ammonia product 255 may be recovered. The energy forrefrigeration section at A6 (e.g., to provide work W3) is supplied byrenewable electricity in this embodiment. After ammonia recovery, a 17t/hr purge 205′ is taken from the remaining gases to allow for removalof impurities; the composition of this purge stream is approximately 25weight % CH₄, 11 weight % H₂, 62 weight % N₂, and 2% weight % NH₃. Theremainder of the gas stream 253 is then recycled back to synthesis loopcompressor(s) C2/C3.

There are four major energy consumers in the process XI of this Example7: (1) regeneration of the amine solution in CO₂ removal 240A, (2) powerto drive the two large compressors, e.g., work W2 and W3 for synthesisloop compressor(s) C2/C3 and refrigeration compressor at A6,respectively, (3) heating (e.g., at feed pretreatment 110) to raise thetemperature of the feed gases and provide the heat of reaction for theprimary reformer at 220, and (4) preheating (e.g., at heating B2) of thefeed before the first ammonia synthesis reactor 250A. Smaller amounts ofenergy are used for a variety of other purposes. Some of the energyrequired for these operations can be obtained by heat exchange withstreams that are being cooled (for example, much of the heat required topreheat (e.g., at heating B1) the methanation reactor feed can beobtained from heat removed when cooling (e.g., at A4) the product gases243 from the same reactor), but the rest must be supplied externally. InExample 7, external energy is supplied in three places: the primaryreformer furnace at primary reforming 220A, an electric heater for theCO₂ removal system at 240A, and renewable electricity used to power thetwo large compressors. The primary reformer furnace consumes 21.1 t/hrof natural gas with a contained chemical energy (high-heating value, orHHV) of 322 MW. 16 MW of electricity is supplied to the CO₂ removalsystem 240A, generating 15 MW of heat at an efficiency of 95%. An amountof 94 MW of electricity is supplied to the large compressors; at anefficiency of 93%, this performs the same work that required 349 MW ofhigh pressure steam 263 in Comparative Example 2. In addition, althoughsome of the reactions are exothermic (e.g., ammonia synthesis at 250A),the net set of reactions for Example 7 is endothermic and requiresroughly 67 MW of energy to be provided. How to most efficiently allocatethe available energy to the various consumers of energy in the processwith the highest efficiency is an engineering problem that can beaddressed by one of skill in the art upon reading this disclosure viacareful matching of temperatures, types of energy, and energy content.Energy can be transferred directly via heat exchange or it can beconverted to steam that can either be used for heat exchange or to domechanical work, such as to drive a compressor. In Example 7 a strategyhas been utilized that maximizes heat exchange between the variousprocess streams; assuming that available heat can be moved efficientlyfrom where it is available to where it is needed at a correspondingtemperature. This represents a maximal heat integration strategy andminimizes external energy inputs, but other arrangements are possible,as will be obvious to one skilled in the art. The use of combustion tosupply some of the external energy input needed for the process comeswith a concomitant disadvantage—the stack or flue gas from thesefurnaces and boilers contains energy that cannot be usefully recoveredbecause of its low temperature and difficulties in condensing water. Forexample, in the process of Example 7, this wasted energy amounts to 64MW, a reduction of 59% over Comparative Example 2. Energy is also lostin several process steps where streams are cooled but the heat cannot beusefully recovered, for example in the final cooling of the productstream from ammonia synthesis reactor at 250A.

Table 3 shows energy use values for the process XI of Example 7. As seenin Table 3, an amount of 322 MW of energy is supplied through thecombustion of natural gas in the reformer furnace at primary reformer220A; in contrast to Comparative Example 2, there is no auxiliaryboiler. An additional 110 MW of energy is supplied as electricity. Ofthe total energy, 67 MW is required to supply the net endothermic heatof reaction. After subtracting this, the available net energy input tothe process for other uses is 365 MW, although a large amount (>400 MW)of energy is also transferred internally from the cooling of hot productstreams to the heating of feed streams. Of the 322 MW consumed in theprimary reformer furnace, the radiant section is used to provide 168 MWto further heat the gases and supply the heat of reaction; an additional90 MW is transferred in the convection section to provide process heat.The remaining 64 MW is lost to the atmosphere in the flue gas; thisrepresents 18% of the total net available energy. An additional 7 MW, or1.9% of the net external energy available, is lost due to inefficienciesin the use of electricity.

As further seen in the data in Table 3, the total fuel gas consumptionis 169,000 tons per year. The combustion of this fuel results in theatmospheric emissions 0.47 million tons of CO₂ annually. An additional1.1 million tons of CO₂ are emitted from the process chemistry itself,giving total CO₂ emissions of 1.57 million tons per year, a decrease of33% over Comparative Example 2. Specific energy consumption aftersubtracting the heat of reaction from fuel and electricity inputs is 9.9GJ per ton of ammonia produced; specific energy consumption calculatedonly on the fuel and electricity inputs is 11.7 GJ per ton of ammoniaproduced. An amount of 18% of the total available energy is lost to theatmosphere from the stack gas, but none is lost due to inefficiencies inthe conversion of steam to mechanical work, in contrast to ComparativeExample 2 where 22% and 37%, respectively, of the energy was lost inthese ways.

Example 8: Primary (SMR) Reforming Only—all Electric

Example 8 is a near-complete electrification process XII as per anembodiment of this disclosure of the ammonia synthesis process describedin Comparative Example 2. In process XII, near-complete electrificationis provided by electric compressors (as in Examples 5-7), an electricfurnace in primary reformer 220A (as in Example 6), and an electricreboiler (as in Example 7). The key elements of this electrified plantXII are shown in FIG. 14; except for the provision of the energy, theprocess is essentially the same as in Comparative Example 2. The processof Example 8 is configured to produce 125 metric tons per hour ofammonia. If operated for a typical 8000 hours in a year, this wouldresult in the production of one million tons of ammonia, althoughvariations in downtime due to upsets and maintenance could increase orreduce this output. This size is typical of large ammonia plants beingbuilt today.

As shown in FIG. 14 (which has been simplified to show only theessential features of the process of this Example 8), 53 metric tons perhour (t/hr) of methane feed 205 are fed to the process; the pretreatmentof this methane feed to remove sulfur and other harmful components wasnot included in the model and is not shown in FIG. 14. An amount of 176t/hr water 211 is vaporized and mixed with the methane feed. Theresulting feed 215 is further preheated (e.g., at feed pretreatment 110)and fed to primary reformer 220A at approximately 690 psia, where CO,CO₂, and H₂ are produced. Energy Q1 is supplied to primary reformer 220Aby electric heating, which supplies the heat of reaction and furtherheats the gases. The product 221 from primary reformer 220A is cooled(e.g., at cooling A1) to approximately 320° C. and passed through twowater gas shift reactors 230, where additional H₂ and CO₂ are formed.The product stream from the water gas shift reactors 230 is furthercooled (e.g., at cooling A2/A3) and then purified in CO₂ removal section240A, where 129 t/hr CO₂ is removed by amine absorption. To releaseabsorbed CO₂ and regenerate the amine solution, a significant amount ofenergy is required. Some of this energy is obtained by heat exchangewith the cooling gas streams from the primary reformer 220A and thewater gas shift reactors 230, but additional energy Q3 must be supplied;in Example 8, this energy is obtained heating with renewableelectricity. The purified product stream 241 from CO₂ removal section240A is heated to approximately 290° C. and fed to methanation unit240B, where the remaining CO (˜0.4 mol %) and CO₂ (˜0.1 mol %) areremoved. After further cooling and drying of methanation product 243 atA4, 109 t/hr of nitrogen 266 is added, and the resulting gas stream 244is combined with recycle gas 253 and compressed in synthesis loopcompressor(s) C2/C3 to 3095 psia; the energy for this compression (e.g.,to provide work W2) is supplied by renewable electricity in thisembodiment. The combined and compressed gas stream 245 is preheated(e.g., at heating B2) to approximately 450° C. and sent to a series ofthree ammonia synthesis reactors 250A in series with interstage cooling;per-pass conversion of nitrogen is 33%. The ammonia-containing productstream 251 is first cooled at A5, allowing for heat recovery for use inheating other process streams, then cooled again with air and coolingwater, and finally cooled to −34° C. using refrigeration at A6 so that125 t/hr liquid ammonia product 255 may be recovered. The energy forrefrigeration section at A6 (e.g., for work W3) is supplied by renewableelectricity in this embodiment. After ammonia recovery, a 17 t/hr purge205′ is taken from the remaining gases to allow for removal ofimpurities; the composition of this purge stream is approximately 25weight % CH₄, 11 weight % H₂, 62 weight % N₂, and 2% weight % NH₃. Theremainder of the gas stream 253 is then recycled back to synthesis loopcompressor(s) C2/C3.

There are four major energy consumers in the process XII of this Example8: (1) regeneration of the amine solution in CO₂ removal 240A, (2) powerto drive the two large compressors, e.g., to provide work W2 and W3 forsynthesis loop compressor(s) C2/C3 and refrigeration compressor at A6,respectively, (3) heating (e.g., at feed pretreatment 110) to raise thetemperature of the feed gases and provide the heat of reaction for theprimary reformer at 220A, and (4) preheating (e.g., at heating B2) ofthe feed before the first ammonia synthesis reactor of 250A. Smalleramounts of energy are used for a variety of other purposes. Some of theenergy required for these operations can be obtained by heat exchangewith streams that are being cooled (for example, much of the heatrequired to preheat (e.g., at heating B1) the methanation reactor feedcan be obtained from heat removed when cooling (e.g., at A4) the productgases 243 from the same reactor), but the rest must be suppliedexternally. In Example 8, external energy is supplied in three places:the electric heating of the primary reformer at 220A, an electric heaterfor the CO₂ removal system at 240A, and renewable electricity used topower the two large compressors; all of this external energy is suppliedby renewable electricity in this embodiment. The primary reformer 220Ais heated electrically; 210 MW of renewable electricity are used togenerate 200 MW of heat. In contrast to Comparative Example 2, there isno convection section in the primary reformer furnace and no flue gaslosses from this heating. In Example 8, 71 MW of electricity is suppliedto the CO₂ removal system 240A, generating 67 MW of heat at anefficiency of 95%. An amount of 94 MW of electricity is supplied to thetwo large compressors; at an efficiency of 93%, this performs the samework that required 349 MW of high pressure steam 263 in ComparativeExample 2. In addition, although some of the reactions are exothermic(e.g., ammonia synthesis at 250A), the net set of reactions for Example8 is endothermic and requires roughly 67 MW of energy to be provided.How to most efficiently allocate the available energy to the variousconsumers of energy in the process with the highest efficiency is anengineering problem that can be addressed by one of skill in the artupon reading this disclosure via careful matching of temperatures, typesof energy, and energy content. Energy can be transferred directly viaheat exchange or it can be converted to steam that can either be usedfor heat exchange or to do mechanical work, such as to drive acompressor. In Example 8 a strategy has been utilized that maximizesheat exchange between the various process streams; assuming thatavailable heat can be moved efficiently from where it is available towhere it is needed at a corresponding temperature. This represents amaximal heat integration strategy and minimizes external energy inputs,but other arrangements are possible, as will be obvious to one skilledin the art. The use of combustion to supply some of the external energyinput needed for the process comes with a concomitant disadvantage—thestack or flue gas from these furnaces and boilers contains energy thatcannot be usefully recovered because of its low temperature anddifficulties in condensing water. However, in the process of Example 8,no energy is lost in the flue gas. Energy is also lost in severalprocess steps where streams are cooled but the heat cannot be usefullyrecovered, for example in the final cooling of the product stream fromammonia synthesis reactor of 250A.

Table 3 shows energy use values for the process XII of Example 8. Asseen in Table 3, an amount of 375 MW of energy is supplied aselectricity. Of the total energy, 67 MW is required to supply the netendothermic heat of reaction. After subtracting this, the available netenergy input to the process for other uses is 308 MW, although a largeamount (>400 MW) of energy is also transferred internally from thecooling of hot product streams to the heating of feed streams. Incontrast to Comparative Example 2, no energy is lost in Example 8 in theconversion of steam to mechanical work or to the atmosphere in the fluegas. An amount of 21 MW, or 6.8% of the net external energy available,is lost due to inefficiencies in the use of electricity.

As further seen in the data in Table 3, there is no fuel gas consumptionin process XII Example 8. Because of this, the combustion of fuel doesnot result in the atmospheric emission of CO₂. 1.1 million tons of CO₂are emitted from the process chemistry itself, giving total CO₂emissions of 1.1 million tons per year, a decrease of 53% overComparative Example 2. Specific energy consumption after subtracting theheat of reaction from the electricity inputs is 8.3 GJ per ton ofammonia produced; specific energy consumption calculated only on theelectricity inputs is 10.2 GJ per ton of ammonia produced. In contrastto Comparative Example 2, no energy is lost to the atmosphere from thestack gas and no energy is lost in the conversion of steam to mechanicalwork.

Example 9: Primary (SMR) Reforming Only—all Electric Plus PSA

As depicted in dashed lines in FIG. 14, to the process described inExample 8, a pressure swing adsorption (PSA) gas separation unit 267 isfurther added to purify the purge gas stream 205′. With a flowrate of16.7 t/hr, this purge gas stream 205′ contains of 11 weight % hydrogen.The gas separation unit 267 consumes 2 MW of electricity, and yields aproduct stream 268 of essentially pure hydrogen. The resulting 1.84 t/hrof purified hydrogen is fed to a fuel cell 270, where the hydrogen isconverted to water 271 and electricity 272 with an electrical efficiencyof 45%, giving continuous production of 33 MW of electricity. The netelectricity (31 MW) is used to supply 8.3% of the 375 MW of electricityrequired for the process XII (see Table 3.)

Example 10: Primary (SMR) Reforming Only—all Electric Plus PSA and H₂Compression/Storage

To the process XII described in Example 8, we further add a pressureswing adsorption (PSA) gas separation unit 267 to purify the purge gasstream 205′. With a flowrate of 16.7 t/hr, this purge gas stream 205′contains of 11 weight % hydrogen. The gas separation unit 267 consumes 2MW of electricity, and yields a product stream 268 of essentially purehydrogen. The resulting 1.84 t/hr of purified hydrogen is compressed bycompressor C4 and stored in storage vessel 280 for use when theavailability of renewable electricity is lower, or when it is moreexpensive. When needed, the stored hydrogen in storage vessel 280 iscombined with the hydrogen in 268 being produced at that time by theprocess, and both are converted to electricity 272 using a fuel cell270. When to use the stored hydrogen for electricity production will bedetermined by a variety of factors. As one possibility, if somerenewable electricity was available on a diurnal basis, 22.1 tonshydrogen could be collected and stored over a twelve hour period. Whenreleased over the next twelve hours and combined with the 1.84 t/hrhydrogen in line 268 still being produced by the process, this wouldresult in approximately 64 MW of electricity 272 being availablecontinuously for the twelve hours. This could supply 170% of the 375 MWof electricity required for the operation of the process XII.

TABLE 2 Results from Comparative Example 1 and Examples 1-4 ComparativeExample 1 Example 1 Example 2 Example 3 Example 4 (values in (values in(values in (values in (values in MW unless MW unless MW unless MW unlessMW unless External energy inputs specified) specified) specified)specified) specified) Fuel to primary reformer furnace 111 111 0 111 0at 220A Fuel to auxiliary boiler 260 617 85 107 0 0 Exothermic net heatof reaction 70 70 70 70 70 Renewable electricity to 0 114 114 114 114compressors Renewable electricity to 0 0 72 0 72 reforming furnace at220A Renewable electricity to CO₂ 0 0 0 72 90 removal system 240A Totalexternal 798 380 363 367 347 Flue gas losses 147 40 22 23 0 Losses dueto inefficiency in 318 0 0 0 0 steam usage Losses due to inefficiency in0 8 12 12 16 electric usage Total natural gas consumption 854,000 t/yr575,000 t/yr 529,000 t/yr 531,000 t/yr 472,000 t/yr Natural gasconsumption for fuel 382,000 t/yr 103,000 t/yr 56,000 t/yr 58,000 t/yr 0t/yr Specific energy consumption, 22.9 GJ/t 10.9 GJ/t 10.5 GJ/t 10.6GJ/t 10.0 GJ/t including heat of reaction Specific energy consumption,not 20.9 GJ/t 8.9 GJ/t 8.4 GJ/t 8.6 GJ/t 8.0 GJ/t including heat ofreaction Total CO₂ emissions 2,280,000 t/yr 1,520,000 t/yr 1,380,000t/yr 1,390,000 t/yr 1,230,000 t/yr CO₂ emissions from utilities1,050,000 t/yr 283,000 t/yr 155,000 t/yr 160,000 t/yr 0 t/yr

TABLE 3 Results from Comparative Example 2 and Examples 5-8 ComparativeExample 2 Example 5 Example 6 Example 7 Example 8 (values in (values in(values in (values in (values in External MW unless MW unless MW unlessMW unless MW unless energy inputs specified) specified) specified)specified) specified) Fuel to primary reformer 322 322 0 322 0 furnaceat 220A Fuel to auxiliary boiler 260 455 18 84 0 0 Endothermic net heatof 67 67 67 67 67 reaction Renewable electricity to 0 94 94 94 94compressors Renewable electricity to 0 0 210 0 210 reforming furnace at220A Renewable electricity to 0 0 0 16 71 CO₂ removal system 240A Totalnet 710 367 321 365 308 available Flue gas 155 68 17 64 0 losses Lossesdue to inefficiency in 262 0 0 0 0 steam usage Losses due toinefficiency in 0 7 17 7 21 electric usage Total natural gas 876,000t/yr 607,000 t/yr 472,000 t/yr 597,000 t/yr 428,000 t/yr consumptionNatural gas consumption for 448,000 t/yr 179,000 t/yr 44,000 t/yr169,000 t/yr 0 t/yr fuel Specific energy 19.2 GJ/t 9.9 GJ/t 8.7 GJ/t 9.9GJ/t 8.3 GJ/t consumption, including heat of reaction Specific energy21.0 GJ/t 11.8 GJ/t 10.5 GJ/t 11.7 GJ/t 10.2 GJ/t consumption, notincluding heat of reaction Total CO₂ emissions 2,330,000 t/yr 1,590,000t/yr 1,220,000 t/yr 1,570,000 t/yr 1,110,000 t/yr CO₂ emissions fromutilities 1,230,000 t/yr 490,000 t/yr 120,000 t/yr 470,000 t/yr 0 t/yr

While various embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thespirit and teachings of the disclosure. The embodiments described hereinare exemplary only, and are not intended to be limiting. Many variationsand modifications of the subject matter disclosed herein are possibleand are within the scope of the disclosure. Where numerical ranges orlimitations are expressly stated, such express ranges or limitationsshould be understood to include iterative ranges or limitations of likemagnitude falling within the expressly stated ranges or limitations(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numericalrange with a lower limit, R_(L) and an upper limit, R_(U) is disclosed,any number falling within the range is specifically disclosed. Inparticular, the following numbers within the range are specificallydisclosed: R=R_(L)+k*(R_(U)-R_(L)), wherein k is a variable ranging from1 percent to 100 percent with a 1 percent increment, i.e., k is 1percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . 50 percent,51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98percent, 99 percent, or 100 percent. Moreover, any numerical rangedefined by two R numbers as defined in the above is also specificallydisclosed. Use of the term “optionally” with respect to any element of aclaim is intended to mean that the subject element is required, oralternatively, is not required. Both alternatives are intended to bewithin the scope of the claim. Use of broader terms such as comprises,includes, having, etc. should be understood to provide support fornarrower terms such as consisting of, consisting essentially of,comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present disclosure. Thus, the claims are a further description andare an addition to the embodiments of the present disclosure. Thediscussion of a reference is not an admission that it is prior art tothe present disclosure, especially any reference that may have apublication date after the priority date of this application. Thedisclosures of all patents, patent applications, and publications citedherein are hereby incorporated by reference, to the extent that theyprovide exemplary, procedural, or other details supplementary to thoseset forth herein.

Additional Disclosure Part I

The particular embodiments disclosed above are illustrative only, as thepresent disclosure may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present disclosure. Alternative embodiments that resultfrom combining, integrating, and/or omitting features of theembodiment(s) are also within the scope of the disclosure. Whilecompositions and methods are described in broader terms of “having”,“comprising,” “containing,” or “including” various components or steps,the compositions and methods can also “consist essentially of” or“consist of” the various components and steps. Use of the term“optionally” with respect to any element of a claim means that theelement is required, or alternatively, the element is not required, bothalternatives being within the scope of the claim.

Numbers and ranges disclosed above may vary by some amount. Whenever anumerical range with a lower limit and an upper limit is disclosed, anynumber and any included range falling within the range are specificallydisclosed. In particular, every range of values (of the form, “fromabout a to about b,” or, equivalently, “from approximately a to b,” or,equivalently, “from approximately a-b”) disclosed herein is to beunderstood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an”, as used in theclaims, are defined herein to mean one or more than one of the elementthat it introduces. If there is any conflict in the usages of a word orterm in this specification and one or more patent or other documents,the definitions that are consistent with this specification should beadopted.

Embodiments disclosed herein include:

A: An ammonia synthesis plant comprising: a feed pretreating sectionoperable to pretreat a feed stream comprising natural gas, methane,propane, butane, LPG, naphtha, coal, petroleum coke, or a combinationthereof; a syngas generation section comprising one or more reformersoperable to reform the feed stream to produce a reformer product streamcomprising carbon monoxide and hydrogen; a shift conversion sectioncomprising one or more shift reactors operable to subject the reformerproduct stream to the water gas shift reaction, to produce a shifted gasstream comprising more hydrogen than the reformer gas stream; apurification section operable to remove at least one component from theshifted gas stream, and provide an ammonia synthesis feed streamcomprising hydrogen and nitrogen; and/or an ammonia synthesis sectioncomprising one or more ammonia synthesis reactors operable to produceammonia from the ammonia synthesis feed stream, wherein the ammoniasynthesis plant is configured such that, relative to a conventionalammonia synthesis plant, more of the energy required by the ammoniasynthesis plant, the feed pretreating section, the syngas generationsection, the shift conversion section, the purification section, theammonia synthesis section, or a combination thereof, is provided by anon-carbon based energy source, a renewable energy source, and/orelectricity.

B: An ammonia synthesis plant comprising: a feed pretreating sectionoperable to pretreat a feed stream comprising a carbon-containingmaterial, such as natural gas, methane, propane, butane, LPG, naphtha,coal and/or petroleum coke; a syngas generation section comprising oneor more reformers operable to the pretreated feed stream to produce areformer gas stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising at least one shift reactor operable tosubject the reformer gas stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and/or an ammoniasynthesis section comprising at least one ammonia synthesis reactoroperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured such that a majorityof the net external energy required by the feed pretreating section, thesyngas generation section, the shift conversion section, thepurification section, the ammonia synthesis section, or a combinationthereof, is provided by electricity.

C: An ammonia synthesis plant comprising: a feed pretreating sectionoperable to pretreat a feed stream; a syngas generation sectioncomprising one or more reformers operable to reform methane to produce areformer gas stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising one or more shift reactors operable tosubject the reformer gas stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a section operable to remove at least one component from theshifted gas stream, and provide an ammonia synthesis feed streamcomprising hydrogen and nitrogen; and/or an ammonia synthesis sectioncomprising one or more ammonia synthesis reactors operable to produceammonia from the ammonia synthesis feed stream, wherein the ammoniasynthesis plant is configured such that no steam is utilized formechanical work.

D: An ammonia synthesis plant comprising: a feed pretreating sectionoperable to pretreat a feed stream; a syngas generation sectioncomprising one or more reformers operable to reform methane to produce areformer gas stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising one or more shift reactors operable tosubject the reformer gas stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a section operable to remove at least one component from theshifted gas stream, and provide an ammonia synthesis feed streamcomprising hydrogen and nitrogen; and/or an ammonia synthesis sectioncomprising one or more ammonia synthesis reactors operable to produceammonia from the ammonia synthesis feed stream, wherein the ammoniasynthesis plant is configured such that no flue gas is produced.

E: An ammonia synthesis plant comprising: a feed pretreating sectionoperable to pretreat a feed stream; a syngas generation sectioncomprising one or more reformers operable to reform methane to produce areformer gas stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising one or more shift reactors operable tosubject the reformer gas stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and/or an ammoniasynthesis section comprising one or more ammonia synthesis reactorsoperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured for no combustionother than optionally within an autothermal reformer (ATR) of the syngasgeneration section.

F: An ammonia synthesis plant comprising an electrically heated steamreformer operable to provide hydrogen and an electrically powered airseparation unit (ASU) operable to provide nitrogen for the ammoniasynthesis.

G: An ammonia synthesis plant comprising: a purification sectionoperable to receive a hydrogen stream and a stream of nitrogen, whereinthe stream of nitrogen is optionally from a source disparate from asource of the hydrogen stream, optionally remove at least one componentfrom the hydrogen stream and/or the nitrogen stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen; and anammonia synthesis section comprising one or more ammonia synthesisreactors operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured such that amajority of the net external energy supplied for compression and heatingwithin the purification section, the ammonia synthesis section, or theentire ammonia synthesis plant, is supplied from a non-carbon basedenergy source, a renewable energy source, electricity, and/or renewableelectricity.

Each of embodiments A, B, C, D, E, F, and G may have one or more of thefollowing additional elements: Element 1: wherein the non-carbon basedenergy source comprises electricity. Element 2: wherein the electricityis produced from a renewable energy source. Element 3: wherein therenewable energy source comprises wind, solar, geothermal,hydroelectric, nuclear, tide, wave, or a combination thereof. Element 4:wherein a desired reforming temperature within at least one of the oneor more reformers can be attained without externally (e.g., in afurnace) combusting a fuel or a carbon-based fuel. Element 5: whereinthe one or more reformers are heated to the desired reformingtemperature via heating from electricity or renewable electricity andincluding associated convective, radiant or other heat transfer means.Element 6: wherein the one or more reactors are heated resistively orinductively. Element 7: wherein, other than the production of steam foruse in a steam methane reformer and/or a pre-reformer, steam is notutilized as a primary energy transfer medium, and/or wherein steam isnot utilized for mechanical work. Element 8: wherein: a majority, some,or all of the steam utilized in a steam methane reformer, apre-reformer, or a combination thereof is produced electrically. Element9: further comprising an electrode boiler and/or an immersion heater forthe production of steam. Element 10: wherein the pretreating section,the syngas generation section, the shift conversion section, thepurification section, the ammonia synthesis section, or a combinationthereof comprises one or more compressors, and wherein at least half ora majority of the one or more compressors are configured fornon-gas-driven and/or non-steam-driven operation and/or are configuredfor operation via steam produced without burning a fuel or acarbon-based fuel. Element 11: wherein at least one of the one or morecompressors are configured for bifunctional operation via both electricmotor-driven and gas-driven or both electric motor-driven and steamdriven operation, and/or comprise at least one electric motor-drivencompressor and at least one gas-driven or steam-driven compressor.Element 12: comprising dual compressors for one or more compression stepof the feed pretreating section, the syngas generation section, theshift conversion section, the hydrogen purification section, the ammoniasynthesis section, or a combination thereof, such that the compressionstep can be effected via a first of the dual compressors that is onlinewhen a second of the dual compressors is offline, and vice versa,wherein the first of the dual compressors is electric motor-driven, andthe second of the dual compressors is steam-driven or combustion-driven.Element 13: wherein configuration of the plant enables operation of oneor more compression step via renewable electricity, when available, andoperation via steam or combustion, when renewable electricity is notavailable. Element 14: wherein the renewable electricity is provided bywind, solar, geothermal, hydroelectric, nuclear, tide, wave, or acombination thereof. Element 15: comprising apparatus for cooling orheating a process stream, wherein a fraction or a majority of theheating apparatus, the cooling apparatus, or both provide heating orcooling electrically. Element 16: wherein the fraction or the majorityof the cooling apparatus comprises cooling apparatus downstream of eachof the one or more reformers; cooling apparatus downstream of a final ofthe one or more reformers; cooling apparatus downstream of a hightemperature shift reactor, a low temperature shift reactor, or both;cooling apparatus downstream of a methanator and configured to condensewater out of a methanator product stream; cooling apparatus downstreamone or more of the one or more ammonia synthesis reactors; or acombination thereof. Element 17: wherein the fraction or the majority ofthe heating apparatus comprises heating apparatus before the one or morereformers; between a carbon dioxide removal apparatus and a methanatorof the purification section; heating apparatus upstream of the one ormore ammonia synthesis reactors; or both. Element 18: wherein energy isstored using compressed hydrogen, compressed natural gas feed, cryogenicliquids, thermal batteries (including high thermal mass furnace liningmaterial), electric batteries, or a combination thereof, such that thestored energy from the hydrogen, the natural gas, the cryogenic liquids,the thermal batteries, and/or electricity can be utilized when renewableelectricity is not available. Element 19: further comprising electricityproduction apparatus configured to produce electricity from pressure orheat within the ammonia synthesis plant. Element 20: wherein theelectricity production apparatus comprises an expander, a thermoelectricdevice, or a combination thereof. Element 21: wherein: the syngasgeneration section comprises a steam methane reformer upstream of anautothermal reformer, wherein a compressor is utilized to compress airfor introduction into the autothermal reformer; the shift conversionsection comprises a high temperature shift reactor upstream of a lowtemperature shift reactor, with cooling apparatus before and after thehigh temperature shift reactor and after the low temperature shiftreactor; the hydrogen purification section comprises a carbon dioxideremoval apparatus upstream of a methanator and separated therefrom via aheating apparatus, and a water condensing apparatus, one or morecompressors, and a heating apparatus downstream of the methanator; theammonia synthesis section comprises one or more ammonia synthesisreactors with heat removal apparatus, a recycle compressor downstreamfrom a last of the one or more ammonia synthesis reactors, and a purgegas system, wherein the purge is taken upstream of the recyclecompressor, wherein a majority of a net heat input needed by the steammethane reformer; a net heat input provided by the heating apparatus; anet heat removal effected by the cooling apparatus, the water condensingapparatus, and/or the purge gas system; or a combination thereof isprovided by electricity; and/or wherein a majority of the compressorsselected from the compressor utilized to compress the air, the one ormore compressors downstream of the methanator, and the recyclecompressor are electric-motor driven and/or driven byelectrically-produced steam. Element 22: comprising no ATR, and furthercomprising an inlet line for nitrogen downstream of the one or morereformers of the syngas generation section. Element 23: comprising noautothermal reformer (ATR). Element 24: further comprising a nitrogeninlet line fluidly connecting the ASU with the one or more ammoniasynthesis reactors, whereby the nitrogen from the ASU can be introducedas a component of a feed to the one or more ammonia synthesis reactors.Element 25: wherein the purification section further comprises amethanator, wherein the nitrogen inlet line is downstream of themethanator. Element 26: wherein an ammonia synthesis loop of the ammoniasynthesis plant is operable with a lower amount of purging than aconventional ammonia synthesis plant.

Additional Disclosure Part II

The following are non-limiting, specific embodiments in accordance withthe present disclosure:

A first embodiment, which is an ammonia synthesis plant comprising afeed pretreating section operable to pretreat a feed stream comprisingnatural gas, methane, propane, butane, LPG, naphtha, coal, petroleumcoke, or a combination thereof, a syngas generation section comprisingone or more reformers operable to reform the feed stream to produce areformer product stream comprising carbon monoxide and hydrogen, a shiftconversion section comprising one or more shift reactors operable tosubject the reformer product stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream, a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen, and/or an ammoniasynthesis section comprising one or more ammonia synthesis reactorsoperable to produce ammonia from the ammonia synthesis feed stream,wherein the ammonia synthesis plant is configured such that, relative toa conventional ammonia synthesis plant, more of the energy required bythe ammonia synthesis plant, the feed pretreating section, the syngasgeneration section, the shift conversion section, the purificationsection, the ammonia synthesis section, or a combination thereof, isprovided by a non-carbon based energy source, a renewable energy source,and/or electricity.

A second embodiment, which is the ammonia synthesis plant of the firstembodiment, wherein the non-carbon based energy source compriseselectricity.

A third embodiment, which is an ammonia synthesis plant comprising afeed pretreating section operable to pretreat a feed stream comprising acarbon-containing material, such as natural gas, methane, propane,butane, LPG, naphtha, coal and/or petroleum coke, a syngas generationsection comprising one or more reformers operable to the pretreated feedstream to produce a reformer gas stream comprising carbon monoxide andhydrogen, a shift conversion section comprising at least one shiftreactor operable to subject the reformer gas stream to the water gasshift reaction, to produce a shifted gas stream comprising more hydrogenthan the reformer gas stream, a purification section operable to removeat least one component from the shifted gas stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen, and/oran ammonia synthesis section comprising at least one ammonia synthesisreactor operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured such that amajority of the net external energy required by the feed pretreatingsection, the syngas generation section, the shift conversion section,the purification section, the ammonia synthesis section, or acombination thereof, is provided by electricity.

A fourth embodiment, which is the ammonia synthesis plant of the secondor the third embodiment, wherein the electricity is produced from arenewable energy source.

A fifth embodiment, which is the ammonia synthesis plant of the fourthembodiment, wherein the renewable energy source comprises wind, solar,geothermal, hydroelectric, nuclear, tide, wave, or a combinationthereof.

A sixth embodiment, which is the ammonia synthesis plant of the secondor the third embodiment, wherein a desired reforming temperature withinat least one of the one or more reformers can be attained withoutexternally (e.g., in a furnace) combusting a fuel or a carbon-basedfuel.

A seventh embodiment, which is the ammonia synthesis plant of the sixthembodiment, wherein the one or more reformers are heated to the desiredreforming temperature via heating from electricity or renewableelectricity and including associated convective, radiant or other heattransfer means.

An eighth embodiment, which is the ammonia synthesis plant of theseventh embodiment, wherein the one or more reactors are heatedresistively or inductively.

A ninth embodiment, which is the ammonia synthesis plant of the secondor the third embodiment wherein, other than the production of steam foruse in a steam methane reformer and/or a pre-reformer, steam is notutilized as a primary energy transfer medium, and/or wherein steam isnot utilized for mechanical work.

A tenth embodiment, which is the ammonia synthesis plant of the secondor the third embodiment, wherein a majority, some, or all of the steamutilized in a steam methane reformer, a pre-reformer, or a combinationthereof is produced electrically.

An eleventh embodiment, which is the ammonia synthesis plant of thetenth embodiment further comprising an electrode boiler and/or animmersion heater for the production of steam.

A twelfth embodiment, which is the ammonia synthesis plant of the secondor the third embodiment, wherein the pretreating section, the syngasgeneration section, the shift conversion section, the purificationsection, the ammonia synthesis section, or a combination thereofcomprises one or more compressors, and wherein at least half or amajority of the one or more compressors are configured fornon-gas-driven and/or non-steam-driven operation and/or are configuredfor operation via steam produced without burning a fuel or acarbon-based fuel.

A thirteenth embodiment, which is the ammonia synthesis plant of thetwelfth embodiment, wherein at least one of the one or more compressorsare configured for bifunctional operation via both electric motor-drivenand gas-driven or both electric motor-driven and steam driven operation,and/or comprise at least one electric motor-driven compressor and atleast one gas-driven or steam-driven compressor.

A fourteenth embodiment, which is the ammonia synthesis plant of thetwelfth embodiment comprising dual compressors for one or morecompression step of the feed pretreating section, the syngas generationsection, the shift conversion section, the hydrogen purificationsection, the ammonia synthesis section, or a combination thereof, suchthat the compression step can be effected via a first of the dualcompressors that is online when a second of the dual compressors isoffline, and vice versa, wherein the first of the dual compressors iselectric motor-driven, and the second of the dual compressors issteam-driven or combustion-driven.

A fifteenth embodiment, which is the ammonia synthesis plant of thetwelfth, the thirteenth, or the fourteenth embodiment, whereinconfiguration of the plant enables operation of one or more compressionstep via renewable electricity, when available, and operation via steamor combustion, when renewable electricity is not available.

A sixteenth embodiment, which is the ammonia synthesis plant of thefifteenth embodiment, wherein the renewable electricity is provided bywind, solar, geothermal, hydroelectric, nuclear, tide, wave, or acombination thereof.

A seventeenth embodiment, which is the ammonia synthesis plant of thesecond or the third embodiment comprising apparatus for cooling orheating a process stream, wherein a fraction or a majority of theheating apparatus, the cooling apparatus, or both provide heating orcooling electrically.

An eighteenth embodiment, which is the ammonia synthesis plant of theseventeenth embodiment, wherein the fraction or the majority of thecooling apparatus comprises cooling apparatus downstream of each of theone or more reformers; cooling apparatus downstream of a final of theone or more reformers; cooling apparatus downstream of a hightemperature shift reactor, a low temperature shift reactor, or both;cooling apparatus downstream of a methanator and configured to condensewater out of a methanator product stream; cooling apparatus downstreamone or more of the one or more ammonia synthesis reactors; or acombination thereof.

A nineteenth embodiment, which is the ammonia synthesis plant of theseventeenth embodiment, wherein the fraction or the majority of theheating apparatus comprises heating apparatus before the one or morereformers; between a carbon dioxide removal apparatus and a methanatorof the purification section; heating apparatus upstream of the one ormore ammonia synthesis reactors; or both.

A twentieth embodiment, which is the ammonia synthesis plant of thesecond or the third embodiment, wherein energy is stored usingcompressed hydrogen, compressed natural gas feed, cryogenic liquids,thermal batteries (including high thermal mass furnace lining material),electric batteries, or a combination thereof, such that the storedenergy from the hydrogen, the natural gas, the cryogenic liquids, thethermal batteries, and/or electricity can be utilized when renewableelectricity is not available.

A twenty-first embodiment, which is the ammonia synthesis plant of thesecond or the third embodiment further comprising electricity productionapparatus configured to produce electricity from pressure or heat withinthe ammonia synthesis plant.

A twenty-second embodiment, which is the ammonia synthesis plant of thetwenty-first embodiment, wherein the electricity production apparatuscomprises an expander, a thermoelectric device, or a combinationthereof.

A twenty-third embodiment, which is the ammonia synthesis plant of thesecond or the third embodiment, wherein the syngas generation sectioncomprises a steam methane reformer upstream of an autothermal reformer,wherein a compressor is utilized to compress air for introduction intothe autothermal reformer, the shift conversion section comprises a hightemperature shift reactor upstream of a low temperature shift reactor,with cooling apparatus before and after the high temperature shiftreactor and after the low temperature shift reactor, the hydrogenpurification section comprises a carbon dioxide removal apparatusupstream of a methanator and separated therefrom via a heatingapparatus, and a water condensing apparatus, one or more compressors,and a heating apparatus downstream of the methanator, the ammoniasynthesis section comprises one or more ammonia synthesis reactors withheat removal apparatus, a recycle compressor downstream from a last ofthe one or more ammonia synthesis reactors, and a purge gas system,wherein the purge is taken upstream of the recycle compressor, wherein amajority of a net heat input needed by the steam methane reformer; a netheat input provided by the heating apparatus; a net heat removaleffected by the cooling apparatus, the water condensing apparatus,and/or the purge gas system; or a combination thereof is provided byelectricity, and/or wherein a majority of the compressors selected fromthe compressor utilized to compress the air, the one or more compressorsdownstream of the methanator, and the recycle compressor areelectric-motor driven and/or driven by electrically-produced steam.

A twenty-fourth embodiment, which is an ammonia synthesis plantcomprising a feed pretreating section operable to pretreat a feedstream, a syngas generation section comprising one or more reformersoperable to reform methane to produce a reformer gas stream comprisingcarbon monoxide and hydrogen, a shift conversion section comprising oneor more shift reactors operable to subject the reformer gas stream tothe water gas shift reaction, to produce a shifted gas stream comprisingmore hydrogen than the reformer gas stream, a section operable to removeat least one component from the shifted gas stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen, and/oran ammonia synthesis section comprising one or more ammonia synthesisreactors operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured such that nosteam is utilized for mechanical work.

A twenty-fifth embodiment, which is an ammonia synthesis plantcomprising a feed pretreating section operable to pretreat a feedstream, a syngas generation section comprising one or more reformersoperable to reform methane to produce a reformer gas stream comprisingcarbon monoxide and hydrogen, a shift conversion section comprising oneor more shift reactors operable to subject the reformer gas stream tothe water gas shift reaction, to produce a shifted gas stream comprisingmore hydrogen than the reformer gas stream, a section operable to removeat least one component from the shifted gas stream, and provide anammonia synthesis feed stream comprising hydrogen and nitrogen; and/oran ammonia synthesis section comprising one or more ammonia synthesisreactors operable to produce ammonia from the ammonia synthesis feedstream, wherein the ammonia synthesis plant is configured such that noflue gas is produced.

A twenty-sixth embodiment, which is an ammonia synthesis plantcomprising a feed pretreating section operable to pretreat a feedstream, a syngas generation section comprising one or more reformersoperable to reform methane to produce a reformer gas stream comprisingcarbon monoxide and hydrogen, a shift conversion section comprising oneor more shift reactors operable to subject the reformer gas stream tothe water gas shift reaction, to produce a shifted gas stream comprisingmore hydrogen than the reformer gas stream, a purification sectionoperable to remove at least one component from the shifted gas stream,and provide an ammonia synthesis feed stream comprising hydrogen andnitrogen; and/or an ammonia synthesis section comprising one or moreammonia synthesis reactors operable to produce ammonia from the ammoniasynthesis feed stream, wherein the ammonia synthesis plant is configuredfor no combustion other than optionally within an autothermal reformer(ATR) of the syngas generation section.

A twenty-seventh embodiment, which is the ammonia synthesis plant of thetwenty-sixth embodiment comprising no ATR, and further comprising aninlet line for nitrogen downstream of the one or more reformers of thesyngas generation section.

A twenty-eighth embodiment, which is an ammonia synthesis plantcomprising an electrically heated steam reformer operable to providehydrogen and an electrically powered air separation unit (ASU) operableto provide nitrogen for the ammonia synthesis.

A twenty-ninth embodiment, which is the ammonia synthesis plant of thetwenty-eighth embodiment comprising no autothermal reformer (ATR).

A thirtieth embodiment, which is the ammonia synthesis plant of thetwenty-ninth embodiment further comprising a nitrogen inlet line fluidlyconnecting the ASU with the one or more ammonia synthesis reactors,whereby the nitrogen from the ASU can be introduced as a component of afeed to the one or more ammonia synthesis reactors.

A thirty-first embodiment, which is the ammonia synthesis plant of thethirtieth embodiment, wherein the purification section further comprisesa methanator, wherein the nitrogen inlet line is downstream of themethanator.

A thirty-second embodiment, which is the ammonia synthesis plant of thetwenty-eighth embodiment, wherein an ammonia synthesis loop of theammonia synthesis plant is operable with a lower amount of purging thana conventional ammonia synthesis plant.

A thirty-third embodiment, which is an ammonia synthesis plantcomprising a purification section operable to receive a hydrogen streamand a stream of nitrogen, wherein the stream of nitrogen is optionallyfrom a source disparate from a source of the hydrogen stream, optionallyremove at least one component from the hydrogen stream and/or thenitrogen stream, and provide an ammonia synthesis feed stream comprisinghydrogen and nitrogen; and an ammonia synthesis section comprising oneor more ammonia synthesis reactors operable to produce ammonia from theammonia synthesis feed stream, wherein the ammonia synthesis plant isconfigured such that a majority of the net external energy supplied forcompression and heating within the purification section, the ammoniasynthesis section, or the entire ammonia synthesis plant, is suppliedfrom a non-carbon based energy source, a renewable energy source,electricity, and/or renewable electricity.

A thirty-fourth embodiment, which is an apparatus and/or a method ofproducing ammonia via the apparatus as described herein and recited inany of the first through the thirty-third embodiments or any of theembodiments described in this disclosure.

Additional Disclosure Part III

The following are non-limiting, specific embodiments in accordance withthe present disclosure:

Embodiments disclosed herein include:

A: A method of producing ammonia, the method comprising: (a) introducinga feed comprising a carbon containing material selected from naturalgas, methane, propane, butane, LPG, naphtha, coal, petroleum coke, orcombinations thereof to a synthesis gas generation section such as steamreforming or partial oxidation to produce a synthesis gas productcomprising hydrogen and carbon monoxide, where the energy required forthe synthesis gas generation section is supplied by a heat input Q1; (b)cooling the reformer product to produce a cooled synthesis gas byeffecting a heat removal Q2; (c) shifting the cooled synthesis gas toproduce a shifted synthesis gas product; (d) cooling the shiftedsynthesis gas by effecting a heat removal Q3 to produce a cooled,shifted synthesis gas; (e) purifying the cooled, shifted synthesis gasby: removing carbon dioxide from the cooled, shifted synthesis gas;heating by a heat input Q4 to produce a heated carbon-dioxide reducedgas; methanating the heated carbon-dioxide reduced gas to produce amethanator product; and cooling and condensing water from the methanatorproduct by a heat removal Q5 to provide a purified gas; (f) compressingthe purified gas; (g) heating the compressed, purified gas by a heatinput Q6 to provide a heated gas; (h) providing an ammonia synthesisfeed comprising the heated gas, wherein the ammonia synthesis feedcomprises hydrogen and nitrogen, wherein the nitrogen is present in thesynthesis gas or subsequently added thereto; (i) producing a productcomprising ammonia from the ammonia synthesis feed; (j) cooling theproduct comprising ammonia by a heat removal Q7 to remove ammonia fromthe product comprising ammonia and provide a recycle gas streamcomprising nitrogen and hydrogen; (k) compressing the gas streamcomprising nitrogen and hydrogen via a recycle compressor; and/or (l)purging via a purge gas system, wherein further cooling is effected by aheat removal Q8, wherein, relative to a conventional method of producingammonia, more of the net energy required by the method or in (a), (b),(c), (d), (e), (f), (g), (h), (i), (j), (k), (l), or a combinationthereof (e.g., net thermal energy required (e.g.,Q1+Q4+Q6−Q2−Q3−Q5−Q7−Q8) and/or the net energy needed for mechanicalwork) is provided by a non-carbon based energy source, a renewableenergy source, and/or electricity.

B: A method of producing ammonia, the method comprising: (a) subjectinga feed comprising a carbon containing material selected from naturalgas, methane, propane, butane, LPG, naphtha, coal, petroleum coke, orcombinations thereof to reforming in a reformer of a synthesis gasgeneration section to produce a reformer product comprising synthesisgas containing hydrogen and carbon monoxide, wherein a reformingtemperature is maintained by a heat input Q1; (b) cooling the reformerproduct to produce a cooled reformer product by effecting a heat removalQ2; (c) shifting the reformer product to produce a shifted synthesisgas; (d) cooling the shifted synthesis gas by effecting a heat removalQ3; (e) purifying the cooled, shifted synthesis gas by: removing carbondioxide from the cooled, shifted synthesis gas; heating by a heat inputQ4 to produce a heated carbon-dioxide reduced gas; methanating theheated carbon-dioxide reduced gas to produce a methanator product; andcooling and condensing water from the methanator product by removing aheat removal Q5 to provide a purified gas; (f) compressing the purifiedgas; (g) heating the compressed, purified gas by a heat input Q6 toprovide a heated gas; (h) providing an ammonia synthesis feed comprisingthe heated gas, wherein the ammonia synthesis feed comprises hydrogenand nitrogen; (i) producing a product comprising ammonia from theammonia synthesis feed; (j) cooling the product comprising ammonia by aheat removal Q7 to remove ammonia from the product comprising ammoniaand provide a recycle gas stream comprising nitrogen and hydrogen; (k)compressing the gas stream comprising nitrogen and hydrogen; and/or (l)purging via a purge gas system, wherein purging is effected by a heatremoval Q8, wherein a majority of the net thermal and/or mechanicalenergy required by the method or one or more of (a)-(l) is provided by anon-carbon based energy source, a renewable energy source, and/orelectricity.

C: A method of producing ammonia, the method comprising: (a) reacting(e.g., via processes such as steam reforming, partial oxidation and ofgasification), a carbon containing material such as natural gas,methane, propane, butane, LPG, naphtha, coal or petroleum coke toproduce a synthesis gas comprising carbon monoxide and hydrogen; (b)shifting the synthesis gas to produce a shifted product comprisingincreased amount of hydrogen; (c) purifying the shifted product toproduce a purified gas comprising a smaller amount of non-hydrogencomponents; and (d) synthesizing ammonia from the purified gas andoptionally additional nitrogen to provide an ammonia product, wherein amajority or greater than or equal to about 40, 50, 60, 70, 80, or 90% ofthe net energy needed in (a), (b), (c), (d), or a combination thereof isprovided by a non-carbon based energy source, a renewable energy source,electricity, or a combination thereof.

D: A method of producing ammonia, the method comprising: introducing afeed comprising a carbon containing material such as natural gas,methane, propane, butane, LPG, naphtha, coal or petroleum coke to asynthesis gas generation section such as steam reforming or partialoxidation to produce a synthesis gas product comprising hydrogen andcarbon monoxide, where the energy required for the synthesis gasgeneration section is supplied by a heat input Q1; cooling the synthesisgas product to produce a cooled synthesis gas by effecting a heatremoval Q2; shifting the cooled synthesis gas to produce a shiftedsynthesis gas product; cooling the shifted synthesis gas product byeffecting a heat removal Q3 to produce a cooled, shifted synthesis gas;purifying the cooled, shifted synthesis gas by: removing carbon dioxidefrom the cooled, shifted synthesis gas; heating by a heat input Q4 toproduce a heated carbon-dioxide reduced gas; methanating the heatedcarbon-dioxide reduced gas to produce a methanator product; and coolingand condensing water from the methanator product by removing a heatremoval Q5 to provide a purified gas; compressing the purified gas;heating the compressed, purified gas by a heat input Q6 to provide aheated gas; providing an ammonia synthesis feed comprising the heatedgas and optionally added nitrogen; producing a product comprisingammonia from the ammonia synthesis feed; cooling the product comprisingammonia by a heat removal Q7 to remove ammonia from the productcomprising ammonia and provide a recycle gas stream comprising nitrogenand hydrogen; compressing the gas stream comprising nitrogen andhydrogen via a recycle compressor; and/or purging via a purge gassystem, wherein further cooling is effected by a heat removal Q8,wherein a majority or substantially all of the heat removed in coolingand water condensation (e.g., Q2, Q3, Q5, Q7, and/or Q8) is used onlyfor heating other streams (e.g., Q1, Q4, and/or Q7) and/or is convertedto electricity.

Each of embodiments A, B, C, and D may have one or more of the followingadditional elements: Element 1: wherein the non-carbon based energysource comprises electricity. Element 2: wherein the electricity isproduced from a renewable energy source. Element 3: wherein therenewable energy source comprises wind, solar, geothermal,hydroelectric, nuclear, tide, wave, or a combination thereof. Element 4:wherein the energy required for the synthesis gas generation section issupplied without combusting a fuel or a carbon-based fuel. Element 5:wherein the non-carbon based energy source comprises or the electricityis produced via an intermittent energy source (IES), and furthercomprising maintaining the temperature of one or more reactors in thesynthesis gas generation section without combusting a fuel or acarbon-based fuel when the IES is available, and maintaining thetemperature of one or more reactors in the synthesis gas generationsection via a stored supply of energy from the IES or by combusting afuel or a carbon-based fuel when the IES is not available. Element 6:wherein the synthesis gas generation is carried out in one or more steamreformers and the necessary energy is supplied via inductive orresistive heating from electricity or renewable electricity andincluding associated convective, radiant or other heat transfer means.Element 7: wherein, other than the optional production of steam for usein the synthesis gas generating section, steam is not utilized as aprimary energy transfer medium; and/or steam is not utilized formechanical work. Element 8: wherein a majority, some, or all of thesteam utilized in the synthesis gas generating section, one or more, amajority, or all steam turbines of the plant, or a combination thereofis produced electrically. Element 9: wherein removing heat does notcomprise the production of steam for use for mechanical work. Element10: wherein compressing the purified gas, compressing the gas streamcomprising nitrogen and hydrogen, compressing air for introduction intothe process, or a combination thereof comprises compressing with acompressor driven by electric motor, an electrically-driven turbine, ora turbine driven by steam produced electrically in at least one, most,or all compressors utilized. Element 11: further comprising utilizing athermoelectric device to convert some of the heat removed at Q2, Q3, Q5,Q7, and/or Q8 to electricity. Element 12: further comprising utilizingelectric heating to control a temperature profile of any or all of anumber of reactors of the synthesis gas generation section, shiftingreactors utilized for shifting, methanation reactors utilized for themethanating, and ammonia synthesis reactors utilized for producing theproduct comprising ammonia from the ammonia synthesis feed. Element 13:wherein at least one of a number of reactors of the synthesis gasgeneration section is operated to at least approximate isothermaloperation. Element 14: wherein a system for removing carbon dioxidecomprises amine recovery, and wherein the amine recovery is effectedwith electric heating. Element 15: wherein the electric heating isperformed by an immersion heater. Element 16: further comprisingproviding some or all of the heat Q1 needed to achieve a reactiontemperature in (a) via feeding steam to one or more reactors of thesynthesis gas generation section, wherein the steam is superheatedelectrically. Element 17: further comprising providing the nitrogen inthe ammonia synthesis feed via an air separation unit (ASU) powered byrenewable electricity, whereby the ammonia synthesis feed has a reducedamount of argon and/or other inert species relative to conventionaloperation. Element 18: wherein the reduced amount of argon and/or otherinerts reduces a purging of an ammonia synthesis loop of the ammoniasynthesis relative to conventional ammonia synthesis. Element 19:further comprising providing the nitrogen in the ammonia synthesis feedby introducing nitrogen from the renewable electrically powered ASUduring or after the purifying of the cooled, shifted synthesis gas.Element 20: further comprising removing methane from the purified gasprior to compressing the purified gas, wherein removing methane from thepurified gas reduces an amount of purging in (l) of an ammonia synthesisloop utilized to produce the product comprising ammonia from the ammoniasynthesis feed. Element 21: further comprising removing the methane fromthe purified gas via a renewable electrically powered methane removalprocess. Element 22: wherein the renewable electrically powered methaneremoval process comprises pressure swing adsorption (PSA). Element 23:further comprising storing natural gas when electricity is availableand/or below a threshold price, and utilizing the stored natural gas asa component of the feed and/or to generate electricity when electricityis unavailable or above the threshold price. Element 24: furthercomprising storing a refrigerant when electricity is available or belowa threshold price and utilizing the refrigerant for cooling to provideheat removal Q2, Q3, Q5, Q7, and/or Q8 when electricity is unavailableor above the threshold price. Element 25: wherein the refrigerantcomprises ammonia. Element 26: further comprising separating hydrogenfrom a purge gas stream and combusting at least a portion of theseparated hydrogen to provide heat, high-temperature steam for use as areactant in syngas generation, or both. Element 27: further comprisingseparating hydrogen from a purge gas stream, and optionally storing atleast a portion of the separated hydrogen and converting the stored atleast a portion of the hydrogen to electricity when other sources ofelectricity are not readily available and/or are not available at adesirable price. Element 28: wherein one or more fuel cells is used forthe conversion of hydrogen to electricity. Element 29: wherein theamount of electricity consumed is greater than or equal to about 25 MW.Element 30: wherein the amount of CO₂ produced per ton of ammonia isless than or equal to about 1.6 tons CO₂ per ton of ammonia produced.Element 31: wherein the specific energy consumption is less than orequal to about 12 GJ per ton of ammonia produced. Element 32: whereinthe total consumption of methane and/or natural gas for both feed andfuel is less than or equal to about 0.65 tons per ton of ammoniaproduced. Element 33: wherein the total consumption of methane and/ornatural gas for fuel is less than or equal to about 0.20 tons per ton ofammonia produced. Element 34: wherein a majority or greater than orequal to about 40, 50, 60, 70, 80, or 90% of the net energy needed forheat removal, heat input, compression, or a combination thereof in (a),(b), (c), (d), or a combination thereof is provided by a non-carbonbased energy source, a renewable energy source, electricity, or acombination thereof. Element 35: wherein (a) synthesis gas generation iseffected without burning a fuel and/or a carbon-based fuel. Element 36:wherein utilizing a non-carbon based energy source, a renewable energysource, electricity, or a combination thereof to provide a majority orgreater than or equal to about 40, 50, 60, 70, 80, or 90% of the netenergy needed in (a), (b), (c), (d), or the combination thereof resultsin a reduction of at least 5, 10, 20, 30, or 40% in greenhouse gasemissions relative to a conventional method of producing ammonia.

Additional Disclosure Part IV

The following are non-limiting, specific embodiments in accordance withthe present disclosure:

A first embodiment, which is a method of producing ammonia, the methodcomprising (a) introducing a feed comprising a carbon containingmaterial selected from natural gas, methane, propane, butane, LPG,naphtha, coal, petroleum coke, or combinations thereof to a synthesisgas generation section such as steam reforming or partial oxidation toproduce a synthesis gas product comprising hydrogen and carbon monoxide,where the energy required for the synthesis gas generation section issupplied by a heat input Q1, (b) cooling the reformer product to producea cooled synthesis gas by effecting a heat removal Q2, (c) shifting thecooled synthesis gas to produce a shifted synthesis gas product, (d)cooling the shifted synthesis gas by effecting a heat removal Q3 toproduce a cooled, shifted synthesis gas, (e) purifying the cooled,shifted synthesis gas by removing carbon dioxide from the cooled,shifted synthesis gas, heating by a heat input Q4 to produce a heatedcarbon-dioxide reduced gas, methanating the heated carbon-dioxidereduced gas to produce a methanator product, and cooling and condensingwater from the methanator product by a heat removal Q5 to provide apurified gas, (f) compressing the purified gas, (g) heating thecompressed, purified gas by a heat input Q6 to provide a heated gas, (h)providing an ammonia synthesis feed comprising the heated gas, whereinthe ammonia synthesis feed comprises hydrogen and nitrogen, wherein thenitrogen is present in the synthesis gas or subsequently added thereto,(i) producing a product comprising ammonia from the ammonia synthesisfeed, (j) cooling the product comprising ammonia by a heat removal Q7 toremove ammonia from the product comprising ammonia and provide a recyclegas stream comprising nitrogen and hydrogen, (k) compressing the gasstream comprising nitrogen and hydrogen via a recycle compressor, and/or(l) purging via a purge gas system, wherein further cooling is effectedby a heat removal Q8, wherein, relative to a conventional method ofproducing ammonia, more of the net energy required by the method or in(a), (b), (c), (d), (e), (f), (g), (h), (i), (j), (k), (l), or acombination thereof (e.g., net thermal energy required (e.g.,Q1+Q4+Q6−Q2−Q3−Q5−Q7−Q8) and/or the net energy needed for mechanicalwork) is provided by a non-carbon based energy source, a renewableenergy source, and/or electricity.

A second embodiment, which is the method of the first embodiment,wherein the non-carbon based energy source comprises electricity.

A third embodiment, which is a method of producing ammonia, the methodcomprising (a) subjecting a feed comprising a carbon containing materialselected from natural gas, methane, propane, butane, LPG, naphtha, coal,petroleum coke, or combinations thereof to reforming in a reformer of asynthesis gas generation section to produce a reformer productcomprising synthesis gas containing hydrogen and carbon monoxide,wherein a reforming temperature is maintained by a heat input Q1, (b)cooling the reformer product to produce a cooled reformer product byeffecting a heat removal Q2, (c) shifting the reformer product toproduce a shifted synthesis gas, (d) cooling the shifted synthesis gasby effecting a heat removal Q3, (e) purifying the cooled, shiftedsynthesis gas by removing carbon dioxide from the cooled, shiftedsynthesis gas, heating by a heat input Q4 to produce a heatedcarbon-dioxide reduced gas, methanating the heated carbon-dioxidereduced gas to produce a methanator product, and cooling and condensingwater from the methanator product by removing a heat removal Q5 toprovide a purified gas, (f) compressing the purified gas, (g) heatingthe compressed, purified gas by a heat input Q6 to provide a heated gas,(h) providing an ammonia synthesis feed comprising the heated gas,wherein the ammonia synthesis feed comprises hydrogen and nitrogen, (i)producing a product comprising ammonia from the ammonia synthesis feed,(j) cooling the product comprising ammonia by a heat removal Q7 toremove ammonia from the product comprising ammonia and provide a recyclegas stream comprising nitrogen and hydrogen, (k) compressing the gasstream comprising nitrogen and hydrogen, and/or (l) purging via a purgegas system, wherein purging is effected by a heat removal Q8, wherein amajority of the net thermal and/or mechanical energy required by themethod or one or more of (a)-(l) is provided by a non-carbon basedenergy source, a renewable energy source, and/or electricity.

A fourth embodiment, which is the method of the second or the thirdembodiment, wherein the electricity is produced from a renewable energysource.

A fifth embodiment, which is the method of the fourth embodiment,wherein the renewable energy source comprises wind, solar, geothermal,hydroelectric, nuclear, tide, wave, or a combination thereof.

A sixth embodiment, which is the method of the second or the thirdembodiment, wherein the energy required for the synthesis gas generationsection is supplied without combusting a fuel or a carbon-based fuel.

A seventh embodiment, which is the method of the sixth embodiment,wherein the non-carbon based energy source comprises or the electricityis produced via an intermittent energy source (IES), and furthercomprising maintaining the temperature of one or more reactors in thesynthesis gas generation section without combusting a fuel or acarbon-based fuel when the IES is available, and maintaining thetemperature of one or more reactors in the synthesis gas generationsection via a stored supply of energy from the IES or by combusting afuel or a carbon-based fuel when the IES is not available.

An eighth embodiment, which is the method of the second or the thirdembodiment, wherein the synthesis gas generation is carried out in oneor more steam reformers and the necessary energy is supplied viainductive or resistive heating from electricity or renewable electricityand including associated convective, radiant or other heat transfermeans.

A ninth embodiment, which is the method of the second or the thirdembodiment wherein, other than the optional production of steam for usein the synthesis gas generating section, steam is not utilized as aprimary energy transfer medium, and/or steam is not utilized formechanical work.

A tenth embodiment, which is the method of the second or the thirdembodiment, wherein a majority, some, or all of the steam utilized inthe synthesis gas generating section, one or more, a majority, or allsteam turbines of the plant, or a combination thereof is producedelectrically.

An eleventh embodiment, which is the method of the second or the thirdembodiment, wherein removing heat does not comprise the production ofsteam for use for mechanical work.

A twelfth embodiment, which is the method of the second or the thirdembodiment, wherein compressing the purified gas, compressing the gasstream comprising nitrogen and hydrogen, compressing air forintroduction into the process, or a combination thereof comprisescompressing with a compressor driven by electric motor, anelectrically-driven turbine, or a turbine driven by steam producedelectrically in at least one, most, or all compressors utilized.

A thirteenth embodiment, which is the method of the second or the thirdembodiment further comprising utilizing a thermoelectric device toconvert some of the heat removed at Q2, Q3, Q5, Q7, and/or Q8 toelectricity.

A fourteenth embodiment, which is the method of the second or the thirdembodiment further comprising utilizing electric heating to control atemperature profile of any or all of a number of reactors of thesynthesis gas generation section, shifting reactors utilized forshifting, methanation reactors utilized for the methanating, and ammoniasynthesis reactors utilized for producing the product comprising ammoniafrom the ammonia synthesis feed.

A fifteenth embodiment, which is the method of the second or the thirdembodiment, wherein at least one of a number of reactors of thesynthesis gas generation section is operated to at least approximateisothermal operation.

A sixteenth embodiment, which is the method of the second or the thirdembodiment, wherein a system for removing carbon dioxide comprises aminerecovery, and wherein the amine recovery is effected with electricheating.

A seventeenth embodiment, which is the method of the sixteenthembodiment, wherein the electric heating is performed by an immersionheater.

An eighteenth embodiment, which is the method of the second or the thirdembodiment further comprising providing some or all of the heat Q1needed to achieve a reaction temperature in (a) via feeding steam to oneor more reactors of the synthesis gas generation section, wherein thesteam is superheated electrically.

A nineteenth embodiment, which is the method of the second or the thirdembodiment further comprising providing the nitrogen in the ammoniasynthesis feed via an air separation unit (ASU) powered by renewableelectricity, whereby the ammonia synthesis feed has a reduced amount ofargon and/or other inert species relative to conventional operation.

A twentieth embodiment, which is the method of the nineteenthembodiment, wherein the reduced amount of argon and/or other inertsreduces a purging of an ammonia synthesis loop of the ammonia synthesisrelative to conventional ammonia synthesis.

A twenty-first embodiment, which is the method of the twentiethembodiment further comprising providing the nitrogen in the ammoniasynthesis feed by introducing nitrogen from the renewable electricallypowered ASU during or after the purifying of the cooled, shiftedsynthesis gas.

A twenty-second embodiment, which is the method of the second or thethird embodiment, further comprising removing methane from the purifiedgas prior to compressing the purified gas, wherein removing methane fromthe purified gas reduces an amount of purging in (l) of an ammoniasynthesis loop utilized to produce the product comprising ammonia fromthe ammonia synthesis feed.

A twenty-third embodiment, which is the method of the twenty-secondembodiment further comprising removing the methane from the purified gasvia a renewable electrically powered methane removal process.

A twenty-fourth embodiment, which is the method of the twenty-thirdembodiment, wherein the renewable electrically powered methane removalprocess comprises pressure swing adsorption (PSA).

A twenty-fifth embodiment, which is the method of the second or thethird embodiment further comprising storing natural gas when electricityis available and/or below a threshold price, and utilizing the storednatural gas as a component of the feed and/or to generate electricitywhen electricity is unavailable or above the threshold price.

A twenty-sixth embodiment, which is the method of the second or thethird embodiment further comprising storing a refrigerant whenelectricity is available or below a threshold price and utilizing therefrigerant for cooling to provide heat removal Q2, Q3, Q5, Q7, and/orQ8 when electricity is unavailable or above the threshold price.

A twenty-seventh embodiment, which is the method of the twenty-sixthembodiment, wherein the refrigerant comprises ammonia.

A twenty-eighth embodiment, which is the method of the second or thethird embodiment further comprising separating hydrogen from a purge gasstream and combusting at least a portion of the separated hydrogen toprovide heat, high-temperature steam for use as a reactant in syngasgeneration, or both.

A twenty-ninth embodiment, which is the method of the second or thethird embodiment, further comprising separating hydrogen from a purgegas stream, and optionally storing at least a portion of the separatedhydrogen and converting the stored at least a portion of the hydrogen toelectricity when other sources of electricity are not readily availableand/or are not available at a desirable price.

A thirtieth embodiment, which is the method of the twenty-ninthembodiment, wherein one or more fuel cells is used for the conversion ofhydrogen to electricity.

A thirty-first embodiment, which is the method of the second or thethird embodiment, wherein the amount of electricity consumed is greaterthan or equal to about 25 MW.

A thirty-second embodiment, which is the method of the first, thesecond, or the third embodiment, wherein the amount of CO₂ produced perton of ammonia is less than or equal to about 1.6 tons CO₂ per ton ofammonia produced.

A thirty-third embodiment, which is the method of the first, the second,or the third embodiment, wherein the specific energy consumption is lessthan or equal to about 12 GJ per ton of ammonia produced.

A thirty-fourth embodiment, which is the method of the first, thesecond, or the third embodiment, wherein the total consumption ofmethane and/or natural gas for both feed and fuel is less than or equalto about 0.65 tons per ton of ammonia produced.

A thirty-fifth embodiment, which is the method of the first, the second,or the third embodiment, wherein the total consumption of methane and/ornatural gas for fuel is less than or equal to about 0.20 tons per ton ofammonia produced.

A thirty-sixth embodiment, which is a method of producing ammonia, themethod comprising (a) reacting (e.g., via processes such as steamreforming, partial oxidation and of gasification), a carbon containingmaterial such as natural gas, methane, propane, butane, LPG, naphtha,coal or petroleum coke to produce a synthesis gas comprising carbonmonoxide and hydrogen, (b) shifting the synthesis gas to produce ashifted product comprising increased amount of hydrogen, (c) purifyingthe shifted product to produce a purified gas comprising a smalleramount of non-hydrogen components, and (d) synthesizing ammonia from thepurified gas and optionally additional nitrogen to provide an ammoniaproduct, wherein a majority or greater than or equal to about 40, 50,60, 70, 80, or 90% of the net energy needed in (a), (b), (c), (d), or acombination thereof is provided by a non-carbon based energy source, arenewable energy source, electricity, or a combination thereof.

A thirty-seventh embodiment, which is the method of the thirty-sixthembodiment, wherein a majority or greater than or equal to about 40, 50,60, 70, 80, or 90% of the net energy needed for heat removal, heatinput, compression, or a combination thereof in (a), (b), (c), (d), or acombination thereof is provided by a non-carbon based energy source, arenewable energy source, electricity, or a combination thereof.

A thirty-eighth embodiment, which is the method of the thirty-sixthembodiment, wherein (a) synthesis gas generation is effected withoutburning a fuel and/or a carbon-based fuel.

A thirty-ninth embodiment, which is the method of the thirty-sixthembodiment, wherein utilizing a non-carbon based energy source, arenewable energy source, electricity, or a combination thereof toprovide a majority or greater than or equal to about 40, 50, 60, 70, 80,or 90% of the net energy needed in (a), (b), (c), (d), or thecombination thereof results in a reduction of at least 5, 10, 20, 30, or40% in greenhouse gas emissions relative to a conventional method ofproducing ammonia.

A fortieth embodiment, which is a method of producing ammonia, themethod comprising introducing a feed comprising a carbon containingmaterial such as natural gas, methane, propane, butane, LPG, naphtha,coal or petroleum coke to a synthesis gas generation section such assteam reforming or partial oxidation to produce a synthesis gas productcomprising hydrogen and carbon monoxide, where the energy required forthe synthesis gas generation section is supplied by a heat input Q1,cooling the synthesis gas product to produce a cooled synthesis gas byeffecting a heat removal Q2, shifting the cooled synthesis gas toproduce a shifted synthesis gas product, cooling the shifted synthesisgas product by effecting a heat removal Q3 to produce a cooled, shiftedsynthesis gas, purifying the cooled, shifted synthesis gas by removingcarbon dioxide from the cooled, shifted synthesis gas, heating by a heatinput Q4 to produce a heated carbon-dioxide reduced gas, methanating theheated carbon-dioxide reduced gas to produce a methanator product, andcooling and condensing water from the methanator product by removing aheat removal Q5 to provide a purified gas, compressing the purified gas,heating the compressed, purified gas by a heat input Q6 to provide aheated gas, providing an ammonia synthesis feed comprising the heatedgas and optionally added nitrogen, producing a product comprisingammonia from the ammonia synthesis feed, cooling the product comprisingammonia by a heat removal Q7 to remove ammonia from the productcomprising ammonia and provide a recycle gas stream comprising nitrogenand hydrogen, compressing the gas stream comprising nitrogen andhydrogen via a recycle compressor, and/or purging via a purge gassystem, wherein further cooling is effected by a heat removal Q8,wherein a majority or substantially all of the heat removed in coolingand water condensation (e.g., Q2, Q3, Q5, Q7, and/or Q8) is used onlyfor heating other streams (e.g., Q1, Q4, and/or Q7) and/or is convertedto electricity.

Additional Disclosure Part V

The following are non-limiting, specific embodiments in accordance withthe present disclosure:

A first embodiment, which is an ammonia synthesis plant comprising afeed pretreating section operable to pretreat a feed stream comprisingnatural gas, methane, propane, butane, LPG, naphtha, coal, petroleumcoke, or a combination thereof, a syngas generation section comprisingone or more reformers operable to reform the feed stream to produce areformer product stream comprising carbon monoxide and hydrogen, a shiftconversion section comprising one or more shift reactors operable tosubject the reformer product stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream, a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen, and an ammonia synthesissection comprising one or more ammonia synthesis reactors operable toproduce ammonia from the ammonia synthesis feed stream, wherein ammoniasynthesis plant consumes greater than or equal to about 25 MW ofelectricity, wherein the amount of CO₂ produced per ton of ammonia isless than or equal to about 1.6 tons CO₂ per ton of ammonia produced,and wherein the specific energy consumption is less than or equal toabout 12 GJ per ton of ammonia produced.

A second embodiment, which is the ammonia synthesis plant according tothe first embodiment, wherein the ammonia synthesis plant has no fluegas heat recovery section.

A third embodiment, which is the ammonia synthesis plant according tothe first or the second embodiment, wherein a predetermined reformingtemperature within at least one of the one or more reformers can beattained without externally combusting a fuel or a carbon-based fuel,and wherein the one or more reformers are heated to the predeterminedreforming temperature via heating from electricity and includingassociated convective, radiant or other heat transfer means.

A fourth embodiment, which is the ammonia synthesis plant according toany of the first through the third embodiments, wherein the one or morereactors are heated inductively.

A fifth embodiment, which is the ammonia synthesis plant according toany of the first through the fourth embodiments, wherein other than theproduction of steam for use in a steam methane reformer or apre-reformer, steam is not utilized as a primary energy transfer medium.

A sixth embodiment, which is the ammonia synthesis plant according toany of the first through the fifth embodiments, wherein at least 25% ofmechanical work performed in the ammonia synthesis plant is accomplishedwithout use of steam. In an aspect, which is the ammonia synthesis plantaccording to the sixth embodiment, at least 25, 30, 40, 50, 60, 70, 80,90, 99, or 100% of mechanical work performed in the ammonia synthesisplant is accomplished without use of steam, for example via one or moreelectrified compressors. In an aspect, which is the ammonia synthesisplant according to the sixth embodiment, at least 50, 60, 70, 80, 90,99, or 100% of mechanical work performed in the ammonia synthesis plantis accomplished without use of steam, for example via two or moreelectrified compressors. In an aspect, which is the ammonia synthesisplant according to the sixth embodiment, at least 50, 60, 70, 80, 90,99, or 100% of mechanical work performed in the ammonia synthesis plantis accomplished without use of steam, for example via three or moreelectrified compressors using equal to or greater than about 100, 110,or 120 MW of electricity.

A seventh embodiment, which is the ammonia synthesis plant according toany of the first through the sixth embodiments, wherein at least 50, 55,60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the steam utilized in asteam methane reformer, a pre-reformer, or a combination thereof isproduced by electric heating.

An eighth embodiment, which is the ammonia synthesis plant according toany of the first through the seventh embodiments, wherein thepretreating section, the syngas generation section, the shift conversionsection, the purification section, the ammonia synthesis section, or acombination thereof comprises one or more compressors, and wherein atleast half of the one or more compressors are configured fornon-gas-driven or non-steam-driven operation or are configured foroperation via steam produced without burning a fuel.

A ninth embodiment, which is the ammonia synthesis plant according toany of the first through the eighth embodiments, wherein energy isstored using compressed hydrogen, compressed natural gas feed, cryogenicliquids, thermal batteries, high thermal mass furnace lining material,electric batteries, or a combination thereof, such that the storedenergy from the hydrogen, the natural gas, the cryogenic liquids, thethermal batteries, and electricity can be utilized in the ammoniasynthesis plant when renewable electricity is not available.

A tenth embodiment, which is the ammonia synthesis plant according toany of the first through the ninth embodiments, further comprisingelectricity production apparatus configured to produce electricity frompressure or heat within the ammonia synthesis plant, and wherein theelectricity production apparatus comprises an expander, a thermoelectricdevice, or a combination thereof.

An eleventh embodiment, which is the ammonia synthesis plant accordingto any of the first through the tenth embodiments, comprising (a) anelectrically heated steam reformer operable to provide hydrogen and anelectrically powered air separation unit (ASU) operable to providenitrogen for the ammonia synthesis, (b) no autothermal reformer (ATR),and (c) a nitrogen inlet line fluidly connecting the ASU with the one ormore ammonia synthesis reactors, whereby the nitrogen from the ASU canbe introduced as a component of a feed to the one or more ammoniasynthesis reactors.

A twelfth embodiment, which is a method of producing ammonia, the methodcomprising (a) introducing a feed comprising a carbon containingmaterial selected from natural gas, methane, propane, butane, LPG,naphtha, coal, petroleum coke, or combinations thereof to a synthesisgas generation section such as steam reforming or partial oxidation toproduce a synthesis gas product comprising hydrogen and carbon monoxide,where the energy required for the synthesis gas generation section issupplied by a heat input Q1, (b) cooling the reformer product to producea cooled synthesis gas by effecting a heat removal Q2, (c) shifting thecooled synthesis gas to produce a shifted synthesis gas product, (d)cooling the shifted synthesis gas by effecting a heat removal Q3 toproduce a cooled, shifted synthesis gas, (e) purifying the cooled,shifted synthesis gas by removing carbon dioxide from the cooled,shifted synthesis gas, heating by a heat input Q4 to produce a heatedcarbon-dioxide reduced gas, methanating the heated carbon-dioxidereduced gas to produce a methanator product, and cooling and condensingwater from the methanator product by a heat removal Q5 to provide apurified gas, (f) compressing the purified gas, (g) heating thecompressed, purified gas by a heat input Q6 to provide a heated gas, (h)providing an ammonia synthesis feed comprising the heated gas, whereinthe ammonia synthesis feed comprises hydrogen and nitrogen, wherein thenitrogen is present in the synthesis gas or subsequently added thereto,(i) producing a product comprising ammonia from the ammonia synthesisfeed, (j) cooling the product comprising ammonia by a heat removal Q7 toremove ammonia from the product comprising ammonia and provide a recyclegas stream comprising nitrogen and hydrogen, (k) compressing the gasstream comprising nitrogen and hydrogen via a recycle compressor, and(l) purging via a purge gas system, wherein further cooling is effectedby a heat removal Q8, wherein the method consumes greater than or equalto about 25 MW of electricity per day, wherein the amount of CO₂produced per ton of ammonia is less than or equal to about 1.6 tons CO₂per ton of ammonia produced, and wherein the specific energy consumptionis less than or equal to about 12 GJ per ton of ammonia produced.

A thirteenth embodiment, which is the method according to the twelfthembodiment, wherein the total consumption of methane and natural gas forboth feed and fuel is less than or equal to about 0.65 tons per ton ofammonia produced.

A fourteenth embodiment, which is the method according to the twelfth orthe thirteenth embodiment, wherein the total consumption of methane andnatural gas for fuel is less than or equal to about 0.20 tons per ton ofammonia produced.

A fifteenth embodiment, which is the method according to any of thetwelfth through the fourteenth embodiments, wherein the energy requiredfor the synthesis gas generation section is supplied without combustinga fuel.

A sixteenth embodiment, which is the method according to any of thetwelfth through the fifteenth embodiments, wherein the non-carbon basedenergy source comprises or the electricity is produced via anintermittent energy source (IES), and further comprising maintaining thetemperature of one or more reactors in the synthesis gas generationsection without combusting a fuel or a carbon-based fuel when the IES isavailable, and maintaining the temperature of one or more reactors inthe synthesis gas generation section via a stored supply of energy fromthe IES or by combusting a fuel or a carbon-based fuel when the IES isnot available.

A seventeenth embodiment, which is the method according to any of thetwelfth through the sixteenth embodiments, further comprising utilizingelectric heating to control a temperature profile of at least onereactor of the synthesis gas generation section, shifting reactorsutilized for shifting, methanation reactors utilized for themethanating, and ammonia synthesis reactors utilized for producing theproduct comprising ammonia from the ammonia synthesis feed.

An eighteenth embodiment, which is the method according to theseventeenth embodiment, wherein at least one of a reactors of thesynthesis gas generation section are operated to at least approximateisothermal operation.

A nineteenth embodiment, which is the method of according to any of thetwelfth through the eighteenth embodiments, further comprising providingsome or all of the heat Q1 needed to achieve a reaction temperature in(a) via feeding steam to one or more reactors of the synthesis gasgeneration section, wherein the steam is superheated electrically.

A twentieth embodiment, which is the method according to any of thetwelfth through the nineteenth embodiments, further comprising removingmethane from the purified gas prior to compressing the purified gas,wherein removing methane from the purified gas reduces an amount ofpurging in (l) of an ammonia synthesis loop utilized to produce theproduct comprising ammonia from the ammonia synthesis feed, wherein theremoving the methane from the purified gas via a renewable electricallypowered methane removal process, and wherein the renewable electricallypowered methane removal process comprises pressure swing adsorption(PSA).

A twenty-first embodiment, which is the method according to any of thetwelfth through the twentieth embodiments, further comprising storingnatural gas when electricity is available and below a threshold price,and utilizing the stored natural gas as a component of the feed or togenerate electricity when electricity is unavailable or above thethreshold price.

A twenty-second embodiment, which is the method according to any of thetwelfth through the twenty-first embodiments, further comprising storinga refrigerant when electricity is available or below a threshold priceand utilizing the refrigerant for cooling to provide heat removal Q2,Q3, Q5, Q7, and Q8 when electricity is unavailable or above thethreshold price, and wherein the refrigerant comprises ammonia.

A twenty-third embodiment, which is the method according to any of thetwelfth through the twenty-second embodiments, further comprisingseparating hydrogen from a purge gas stream, and storing at least aportion of the separated hydrogen and converting the stored at least aportion of the hydrogen to electricity when other sources of electricityare not readily available or are not available at a desirable price,wherein one or more fuel cells is used for the conversion of hydrogen toelectricity.

A twenty-fourth embodiment, which is the method according to any of thetwelfth through the twenty-third embodiments, wherein a system forremoving carbon dioxide comprises amine recovery, and wherein the aminerecovery is effected with electric heating.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the teachings of this disclosure. The embodimentsdescribed herein are exemplary only, and are not intended to belimiting. Many variations and modifications of the invention disclosedherein are possible and are within the scope of the invention.

Numerous other modifications, equivalents, and alternatives, will becomeapparent to those skilled in the art once the above disclosure is fullyappreciated. It is intended that the following claims be interpreted toembrace all such modifications, equivalents, and alternatives whereapplicable. Accordingly, the scope of protection is not limited by thedescription set out above but is only limited by the claims whichfollow, that scope including all equivalents of the subject matter ofthe claims. Each and every claim is incorporated into the specificationas an embodiment of the present invention. Thus, the claims are afurther description and are an addition to the detailed description ofthe present invention. The disclosures of all patents, patentapplications, and publications cited herein are hereby incorporated byreference.

What is claimed is:
 1. An ammonia synthesis plant comprising: a feedpretreating section operable to pretreat a feed stream comprisingnatural gas, methane, propane, butane, LPG, naphtha, coal, petroleumcoke, or a combination thereof; a syngas generation section comprisingone or more reformers operable to reform the feed stream to produce areformer product stream comprising carbon monoxide and hydrogen; a shiftconversion section comprising one or more shift reactors operable tosubject the reformer product stream to the water gas shift reaction, toproduce a shifted gas stream comprising more hydrogen than the reformergas stream; a purification section operable to remove at least onecomponent from the shifted gas stream, and provide an ammonia synthesisfeed stream comprising hydrogen and nitrogen; and an ammonia synthesissection comprising one or more ammonia synthesis reactors operable toproduce ammonia from the ammonia synthesis feed stream, wherein ammoniasynthesis plant consumes greater than or equal to about 25 MW ofelectricity, wherein the amount of CO₂ produced per ton of ammonia isless than or equal to about 1.6 tons CO₂ per ton of ammonia produced,and wherein the specific energy consumption is less than or equal toabout 12 GJ per ton of ammonia produced.
 3. The ammonia synthesis plantaccording to claim 1, wherein the ammonia synthesis plant has no fluegas heat recovery section.
 3. The ammonia synthesis plant according toclaim 1, wherein a predetermined reforming temperature within at leastone of the one or more reformers can be attained without externallycombusting a fuel or a carbon-based fuel, and wherein the one or morereformers are heated to the predetermined reforming temperature viaheating from electricity and including associated convective, radiant orother heat transfer means.
 4. The ammonia synthesis plant according toclaim 1, wherein the one or more reactors are heated inductively.
 5. Theammonia synthesis plant according to claim 1, wherein other than theproduction of steam for use in a steam methane reformer or apre-reformer, steam is not utilized as a primary energy transfer medium.6. The ammonia synthesis plant according to claim 1, wherein at least25% of mechanical work performed in the ammonia synthesis plant isaccomplished without use of steam.
 7. The ammonia synthesis plantaccording to claim 1, wherein at least 50% of the steam utilized in asteam methane reformer, a pre-reformer, or a combination thereof isproduced by electric heating.
 8. The ammonia synthesis plant accordingto claim 1, wherein the pretreating section, the syngas generationsection, the shift conversion section, the purification section, theammonia synthesis section, or a combination thereof comprises one ormore compressors, and wherein at least half of the one or morecompressors are configured for non-gas-driven or non-steam-drivenoperation or are configured for operation via steam produced withoutburning a fuel.
 9. The ammonia synthesis plant according to claim 1,wherein energy is stored using compressed hydrogen, compressed naturalgas feed, cryogenic liquids, thermal batteries, high thermal massfurnace lining material, electric batteries, or a combination thereof,such that the stored energy from the hydrogen, the natural gas, thecryogenic liquids, the thermal batteries, and electricity can beutilized in the ammonia synthesis plant when renewable electricity isnot available.
 10. The ammonia synthesis plant according to claim 1,further comprising electricity production apparatus configured toproduce electricity from pressure or heat within the ammonia synthesisplant, and wherein the electricity production apparatus comprises anexpander, a thermoelectric device, or a combination thereof.
 11. Theammonia synthesis plant according to claim 1, comprising (a) anelectrically heated steam reformer operable to provide hydrogen and anelectrically powered air separation unit (ASU) operable to providenitrogen for the ammonia synthesis, (b) no autothermal reformer (ATR),and (c) a nitrogen inlet line fluidly connecting the ASU with the one ormore ammonia synthesis reactors, whereby the nitrogen from the ASU canbe introduced as a component of a feed to the one or more ammoniasynthesis reactors.
 12. A method of producing ammonia, the methodcomprising: (a) introducing a feed comprising a carbon containingmaterial selected from natural gas, methane, propane, butane, LPG,naphtha, coal, petroleum coke, or combinations thereof to a synthesisgas generation section such as steam reforming or partial oxidation toproduce a synthesis gas product comprising hydrogen and carbon monoxide,where the energy required for the synthesis gas generation section issupplied by a heat input Q1; (b) cooling the reformer product to producea cooled synthesis gas by effecting a heat removal Q2; (c) shifting thecooled synthesis gas to produce a shifted synthesis gas product; (d)cooling the shifted synthesis gas by effecting a heat removal Q3 toproduce a cooled, shifted synthesis gas; (e) purifying the cooled,shifted synthesis gas by: removing carbon dioxide from the cooled,shifted synthesis gas; heating by a heat input Q4 to produce a heatedcarbon-dioxide reduced gas; methanating the heated carbon-dioxidereduced gas to produce a methanator product; and cooling and condensingwater from the methanator product by a heat removal Q5 to provide apurified gas; (f) compressing the purified gas; (g) heating thecompressed, purified gas by a heat input Q6 to provide a heated gas; (h)providing an ammonia synthesis feed comprising the heated gas, whereinthe ammonia synthesis feed comprises hydrogen and nitrogen, wherein thenitrogen is present in the synthesis gas or subsequently added thereto;(i) producing a product comprising ammonia from the ammonia synthesisfeed; (j) cooling the product comprising ammonia by a heat removal Q7 toremove ammonia from the product comprising ammonia and provide a recyclegas stream comprising nitrogen and hydrogen; (k) compressing the gasstream comprising nitrogen and hydrogen via a recycle compressor; and(l) purging via a purge gas system, wherein further cooling is effectedby a heat removal Q8, wherein the method consumes greater than or equalto about 25 MW of electricity per day, wherein the amount of CO₂produced per ton of ammonia is less than or equal to about 1.6 tons CO₂per ton of ammonia produced, and wherein the specific energy consumptionis less than or equal to about 12 GJ per ton of ammonia produced. 13.The method according to claim 12, wherein the total consumption ofmethane and natural gas for both feed and fuel is less than or equal toabout 0.65 tons per ton of ammonia produced.
 14. The method according toclaim 12, wherein the total consumption of methane and natural gas forfuel is less than or equal to about 0.20 tons per ton of ammoniaproduced.
 15. The method according to claim 12, wherein the energyrequired for the synthesis gas generation section is supplied withoutcombusting a fuel.
 16. The method according to claim 12, wherein thenon-carbon based energy source comprises or the electricity is producedvia an intermittent energy source (IES), and further comprisingmaintaining the temperature of one or more reactors in the synthesis gasgeneration section without combusting a fuel or a carbon-based fuel whenthe IES is available, and maintaining the temperature of one or morereactors in the synthesis gas generation section via a stored supply ofenergy from the IES or by combusting a fuel or a carbon-based fuel whenthe IES is not available.
 17. The method according to claim 12, furthercomprising utilizing electric heating to control a temperature profileof at least one reactor of the synthesis gas generation section,shifting reactors utilized for shifting, methanation reactors utilizedfor the methanating, and ammonia synthesis reactors utilized forproducing the product comprising ammonia from the ammonia synthesisfeed.
 18. The method according to claim 17, wherein at least one of areactors of the synthesis gas generation section are operated to atleast approximate isothermal operation.
 19. The method of according toclaim 12, further comprising providing some or all of the heat Q1 neededto achieve a reaction temperature in (a) via feeding steam to one ormore reactors of the synthesis gas generation section, wherein the steamis superheated electrically.
 20. The method according to claim 12,further comprising removing methane from the purified gas prior tocompressing the purified gas, wherein removing methane from the purifiedgas reduces an amount of purging in (l) of an ammonia synthesis looputilized to produce the product comprising ammonia from the ammoniasynthesis feed, wherein the removing the methane from the purified gasvia a renewable electrically powered methane removal process, andwherein the renewable electrically powered methane removal processcomprises pressure swing adsorption (PSA).
 21. The method according toclaim 12, further comprising storing natural gas when electricity isavailable and below a threshold price, and utilizing the stored naturalgas as a component of the feed or to generate electricity whenelectricity is unavailable or above the threshold price.
 22. The methodaccording to claim 12, further comprising storing a refrigerant whenelectricity is available or below a threshold price and utilizing therefrigerant for cooling to provide heat removal Q2, Q3, Q5, Q7, and Q8when electricity is unavailable or above the threshold price, andwherein the refrigerant comprises ammonia.
 23. The method according toclaim 12, further comprising separating hydrogen from a purge gasstream, and storing at least a portion of the separated hydrogen andconverting the stored at least a portion of the hydrogen to electricitywhen other sources of electricity are not readily available or are notavailable at a desirable price, wherein one or more fuel cells is usedfor the conversion of hydrogen to electricity.
 24. The method accordingto claim 12, wherein a system for removing carbon dioxide comprisesamine recovery, and wherein the amine recovery is effected with electricheating.